Evidence-based clinical practice guidelines for polycystic kidney disease 2014

ADPKD is the most common hereditary cystic kidney disease. ADPKD is characterized by the progressive development of fluid-filled cysts derived from renal tubular epithelial cells and the development of disorders in several organs. Bilateral renal cysts enlarge progressively, gradually compromising renal function, and finally, end-stage renal disease (ESRD) requiring renal replacement therapy occurs in approximately 50 % of patients by the age of 60 years. 
 
The pattern of transmission in ADPKD is autosomal dominant inheritance. A male or female with a mutant allele develops the disease. In case that both parents are unaffected, disease in the offspring results from new mutation. 
 
ADPKD is caused by a germ line mutation in PKD1 (16p13.3)(85 % of cases) or PKD2 (4q21)(15 % of cases).

the backdrop for the 2014 Clinical Practice Guidelines for Polycystic Kidney Disease, which were drawn up to answer the questions of physicians specializing in renal care.

The intended purpose, anticipated users, and predicted social significance of the guidelines
The 2014 Clinical Practice Guidelines for Polycystic Kidney Disease were drawn up to assist renal care specialists with daily diagnosis and treatment of ADPKD and ARPKD. These Guidelines offer descriptive and exhaustive coverage of PKD diagnosis and definition, epidemiology, and screening. Moreover, routine treatment by renal specialists is addressed through clinical questions (CQs) and responses. Each response is accompanied by a recommendation grade reflecting the level of evidence the response embodies. Our objective is to convey standardized care through specific responses to renal specialists' questions, thereby supporting these professionals as they face daily clinical decisions. We anticipate that general practitioners using the current Guidelines along with the 2010 Clinical Guidelines for Polycystic Kidney Disease will deepen their understanding of PKD and liaise more smoothly with renal specialists. The Guidelines should also enhance patients' understanding of the disease and serve as a reference in answering their questions concerning current treatments.
Professional literature and international conferences afford renal specialists fragmented bits of information about the field, while the specialists are expected to have an integrated understanding of the expertise level and medical environment in Japan, and to provide optimal care for each patient. The current Guidelines incorporate the wisdom of experienced specialists, offering not only evidence, but also practical and standardized views communicated to readers through the CQ responses. However, the degree to which information in these Guidelines may be applied to individual patients requires the judgment of each specialist. Patients do not expect uniform, rigid treatment. Indeed, these Guidelines are not intended to restrict the treatment options available to renal specialists, but rather to facilitate treatment based on their own flexible insights and expert understanding. We must also clarify that the Guidelines are not designed for use in resolving medical practice disputes or as evaluation criteria in malpractice lawsuits.

Patients within the scope of the guidelines
These Guidelines apply to any and all PKD patients. Section ''Origins of the guidelines'', ''The intended purpose, anticipated users, and predicted social significance of the guidelines'' ''Patients within the scope of the guidelines'' and ''Preparation procedure'' address ADPKD, whereas Sections ''Contents of the guideline'', ''Evidence levels and recommendation grades'', ''Issues on the preparation of this guideline'', ''Financial sources and conflict of interest'' and ''Publication and future revisions'' cover ARPKD. The Guidelines provide an outline and definition (''Origins of the guidelines'' and ''Contents of the guideline'' section) for each of the two diseases, along with information on diagnosis (''The intended purpose, anticipated users, and predicted social significance of the guidelines'' and ''Evidence levels and recommendation grades'' section), epidemiology (''Patients within the scope of the guidelines'' and ''Issues on the preparation of this guideline'' section), and treatment (''Preparation procedure'' and ''Publication and future revisions'' section). Each section applies to patients regardless of gender or age. However, the Guidelines do not generally take pregnancy into account.

Preparation procedure
Guidelines on four diseases (IgA nephropathy, nephrotic syndrome, RPGN, and polycystic kidney disease [PKD]) were created simultaneously by a research group on progressive kidney disorders (led by Seiichi Matsuo) funded by the Ministry of Health, Labour, and Welfare's research project for overcoming intractable diseases. All of these guidelines have the same chapter structure. PKD is a genetic disease, so Shinshu University professor Yoshimitsu Fukushima assisted by serving on the drafting committee as a representative of the Japan Society of Human Genetics. Keiichi Furukawa of the Division of Infectious Diseases in the Department of Internal Medicine at St. Luke's International Hospital provided assistance regarding cyst infections. We would like to take this opportunity to thank these two physicians for their generous help.
Seventeen CQ were created based on questions the committee members had from actual clinical practice. These guidelines were completed owing to the dedication and effort of the physicians who served on the PKD working group. We thank them again for their efforts (shown separately: 2014 evidence-based PKD clinical guidelines committee).

Contents of the guideline
Guidelines on four diseases (IgA nephropathy, nephrotic syndrome, RPGN, and PKD) with the same format and structure were drafted by a research group on progressive kidney disorders (led by Seiichi Matsuo) funded by the Ministry of Health, Labour, and Welfare's research project for overcoming intractable diseases. As described earlier, the first half (chapters 1-4) addresses ADPKD and the second half (chapters 5-8) addresses ARPKD.

Evidence levels and recommendation grades
Evidence was classified into six levels based on the study design, and was arranged roughly from the most reliable study type (Level 1) to the least reliable (Level 6). These levels do not necessarily represent rigorous scientific standards; they are intended for use as a convenient reference for quickly assessing the significance of various clinical data during the physician's decision-making process.
[Evidence Levels] Level 1: Systematic review/meta-analysis. Level 2: At least one randomized controlled trial (RCT). Level 3: A non-RCT. Level 4: An analytical epidemiologic study (cohort study or case-control study) or a single-arm intervention study (no controls). Level 5: A descriptive study (case report or case series). Level 6: Opinion of an expert committee or an individual expert, which is not based on patient data.
However, for a systematic review/meta-analysis, the evidence level was decided based on the designs of the underlying studies. If the underlying study designs were mixed, the lowest level underlying study was used to determine the overall evidence level. For example, a metaanalysis of cohort studies would be Level 4, but the same Level 4 would also be assigned to a meta-analysis including both RCTs and cohort studies.
In addition, a decision based on committee consensus was that all sub-analyses and post-hoc analyses of RCTs should be categorized at evidence Level 4. Accordingly, it was decided that the evidence level of findings representing the primary endpoints of an RCT would be Level 2, but the evidence level of findings determined via a sub analysis or post-hoc analysis of that RCT would be Level 4.
When a statement related to a certain treatment was presented, consideration was given to the level of the evidence serving as the basis of that statement, and a recommendation grade was assigned as outlined below: [ If we found only a weak scientific basis for a certain statement concerning a treatment, the members of the committee discussed the matter and decided on C1 or C2 for the recommendation grade. Thus, discrimination between C1 and C2 statements was based on expert consensus.

Issues on the preparation of this guideline
(1) Paucity of evidence Little evidence exists for PKD, and only few large clinical studies have been performed globally, apart from a small number in the United States and Europe. For the most part, little evidence substantiates the recommendations in the CQ. In particular, almost no evidence comes from Japan. Whether the results of clinical research from the West can be applied as is to Japan is a question that deserves careful consideration. In creating these guidelines, we strove to ensure that they would not deviate greatly from the clinical practice in Japan.

(2) Issues on medical resources
In general, the clinical guideline must consider medical resources associated with recommended statements. However, the current guideline did not discuss issues on medical cost; thus medical financial problems did not affect the contents of our guideline. In the next guideline, this point may be included.

(3) Guideline reflecting the opinions of patients
During the preparation processes of the clinical guideline, we needed to introduce the opinions of patients. However, this time, we unfortunately could not include the opinions of patients. We should refer to the opinions of patients in the next guideline, particularly in the case that the guideline is used for patients.

Financial sources and conflict of interest
The funds used in creating the guidelines were provided by a research group on progressive kidney disorders funded by the Ministry of Health, Labour, and Welfare's research project for overcoming intractable diseases. These funds were used to pay for transportation to and from meetings, to rent space for meetings, and for box lunches and snacks. The committee members received no compensation. Everyone involved in creating the guidelines (including referees) submitted conflict-of-interest statements based on academic society rules, which are managed by JSN. Opinions were sought from multiple referees and related academic societies to prevent the guidelines from being influenced by any conflicts of interest. Drafts were shown to the society members, and revisions were made based on their opinions (public comments).

Publication and future revisions
The Guidelines were published in the Japanese-language journal of the Japanese Society of Nephrology and concurrently released as a Japanese-language book (by Tokyo Igakusha, Tokyo). The Guidelines were also uploaded to the homepage of the Japanese Society of Nephrology.
At present, CKD-related evidence is being rapidly accumulated, and this new evidence will necessitate the preparation of an updated version of the Guidelines in 3-5 years. A certain degree of turnover in the membership of the revision committee will be required in order to ensure the impartiality of the Guidelines.

Disease concept and definition of ADPKD
ADPKD is the most common hereditary cystic kidney disease. ADPKD is characterized by the progressive development of fluid-filled cysts derived from renal tubular epithelial cells and the development of disorders in several organs. Bilateral renal cysts enlarge progressively, gradually compromising renal function, and finally, endstage renal disease (ESRD) requiring renal replacement therapy occurs in approximately 50 % of patients by the age of 60 years.
The pattern of transmission in ADPKD is autosomal dominant inheritance. A male or female with a mutant allele develops the disease. In case that both parents are unaffected, disease in the offspring results from new mutation.

Diagnosis of ADPKD: symptoms and laboratory findings (1) Algorithm
The diagnostic algorithm for ADPKD is depicted in the Fig. 1. Family history, while important in ADPKD diagnosis, often cannot be assessed. Moreover, even in the absence of family history, it is important to remain alert to newly reported mutations in PKD1/PKD2 genes responsible for disease onset. It can be difficult to detect cysts meeting diagnostic criteria in younger patients, requiring Fig. 1 The algorithm for diagnosis of ADPKD patients reexamination. Clinical questions (CQs) are appended to these guidelines as a reference in following the algorithm and determining treatment and other medical care once a definitive diagnosis has been made.
(2) Diagnostic criteria Table 1 presents the diagnostic criteria of ADPKD (ADPKD Diagnostic Guidelines, Second Edition, published by a Grant-in-Aid for Progressive Renal Diseases Research, Ministry of Health, Labour and Welfare of Japan). Confirmation or nonconfirmation of family history determines one of two possible protocols, each requiring its own distinctive cyst assessment based not only on ultrasonography (US) but also on computed tomography (CT) and magnetic resonance imaging (MRI). In most cases, cysts manifest bilaterally and diagnosis is uncomplicated; in the remaining cases, diagnosis should be carefully performed in accordance with the diagnostic criteria noted herein.
(3) Comparison of diagnostic criteria between Japan and other countries Following Bear's diagnostic criteria in 1984, numerous other versions have been reported, each with its own emphasis on, for example, age classification or cyst assessment through imaging. Ravine's criteria, which were utilized for some time, were the first guidelines reflecting age as a factor. However, Ravine only incorporated PKD1 family history. Although PKD1 and PKD2 mutations each result in almost the same clinical manifestation of the disease, PKD1 progresses to ESRD more rapidly and produces more cysts, leading Pei to incorporate both PKD1 and PKD2 families in his diagnostic criteria. Diagnosis in Western countries combining US with genetic testing is highly credible and should serve as a reference, but its applicability to Japanese patients has not yet been demonstrated.

(4) Testing
ADPKD screening should include family history of renal disease (end-stage and otherwise) and intracranial hemorrhage/cerebrovascular disease; patient history of hypertension, cerebrovascular disease, urinary tract infection, fever, and lower back pain; subjective symptoms such as macroscopic hematuria, lower back and/or flank pain, abdominal distension, headache, edema, and nausea; physical examination to determine blood pressure, abdominal girth, heartbeat, abdominal findings, and edema; blood and urine tests, screening for urinary sediment, proteinuria, and microalbuminuria; estimated glomerular filtration rate (eGFR) and other renal function tests; and screening for intracranial aneurysm through cranial MR angiography. US represents the simplest form of diagnostic imaging for kidney diseases. Other tests to be performed, as appropriate, should include measurement of N-acetyl beta-glucosaminidase and urinary beta2 microglobulin values, MRI, and kidney CT imaging.

(5) Diagnostic imaging
US is the standard screening technique for ADPKD diagnosis and evaluation, but evaluation of kidney size, as opposed to function, is reportedly the better measurement in the evaluation of progression, with CT or MRI recommended for follow-up evaluation. The latter methods surpass US in detecting smaller cysts; MRI can detect cysts with a diameter of 2 mm through T2-weighted imaging. Each Table 1 The Diagnostic imaging is also clinically important in terms of disease complications such as cerebral aneurysms. As adverse reactions can occur, careful consideration must be given to the risk-benefit balance before utilizing contrast media. MRA is useful in screening for cerebral aneurysms and is a noninvasive test with the great benefit of not requiring contrast media. If imaging performed after a definitive ADPKD diagnosis is strictly for follow-up observation, a simple CT once every 2-5 years would be adequate if total kidney volume (TKV) is B1000 mL. If TKV exceeds 1000 mL, CT once every year or two would be appropriate. For screening purposes, diagnostic imaging at the age of 30 years is recommended.

(6) Differential diagnosis
A patient's clinical manifestation and diagnostic imaging should be used to rule out possibilities such as multiple simple renal cysts, acquired cystic kidney disease, and tuberous sclerosis ( Table 2). Particular caution is needed when considering tuberous sclerosis, as approximately 30 % of patients with this disease are said to have no typical symptoms other than renal cysts, which are mistakenly attributed to ADPKD. Additional diseases to be ruled out include renal tubular acidosis, multicystic kidney (multicystic dysplastic kidney), multilocular cyst of the kidney, medullary cystic kidney disease, and oral-facial-digital syndrome. As rare diseases are difficult to identify and distinguish during normal medical examinations, despite reports on characteristic indicators other than renal cysts, extra care should be given during differential diagnosis.

(7) Genetic diagnosis
ADPKD is an autosomal dominant genetic disease. Responsible genes for ADPKD were already identified. Diagnosis of ADPKD in typical cases is easy by detecting multiple cysts in both kidneys. In Japan, genetic diagnostic tests for ADPKD are only available for basic research but not for clinical practice. Physicians must consider whether samples for genetic testing should be sent to foreign laboratories.

(8) Diagnostic imaging for infants and young adults
Diagnostic criteria, including imaging, for ADPKD in infants and young adults have not been established. Screening imaging tests are not recommended for nonsymptomatic infants and young adults, even if they are children of ADPKD patients.

(9) Initial symptoms
Cysts are said to form in utero, with most progressing asymptomatically until the patients are in their 30 or 40 s. Subjective symptoms include abdominal or lower back pain, macroscopic hematuria (including its posttraumatic form caused by sports activities), or abdominal bloating. Acute pain is usually attributable to hemorrhagic cysts, infection, or urinary tract stones. Chronic pain is defined as persistent pain for 4-6-weeks. It occurs in approximately 60 % of ADPKD cases and is usually attributable to cysts. Macroscopic hematuria occurs in approximately 50 % of all cases. Hypertension, diagnosed objectively by physical examination and other methods, is a significant initial symptom (or findings).  3. ADPKD: epidemiology and prognosis (prevalence, incidence, renal prognosis, and vital prognosis) The number of ADPKD patients in Japan who visited hospitals was estimated to be 14,594, yielding an ADPKD prevalence of 116.7 cases per million population at the end of 1994. The total number of ADPKD patients including those who will visit hospitals in the future was estimated to be 31,000. It was suggested that ADPKD affected one individual per 4033 population in Japan. ADPKD was diagnosed in 40 residents of Olmsted County between 1935 and 1980, resulting in an age-and sex-adjusted annual incidence rate of 1.38 case per 100,000 person-years. Approximately 50 % of the patients developed ESRD at the age of 60-69 years. The most common causes of death in ADPKD were infection, sepsis, and cardiac disease (myocardial infarction and congestive heart failure). The survival of ADPKD patients undergoing dialysis surpasses that of general dialysis patients.

ADPKD: treatment and management of complications
(1) Treatment to control the development of ADPKD Hypertension in ADPKD is frequent and develops at a young age, in contrast to essential hypertension. In addition, it is often detected when renal function is normal and cysts are still small. Antihypertensive treatment is generally performed. It is thought that antihypertensive treatment may slow the deterioration of renal function in ADPKD with hypertension. However, because the evidence related to the recommended antihypertensive agents and target blood pressure is inconclusive, we recommend that antihypertensive treatment in ADPKD should follow that administered for chronic kidney disease (CKD).

CQ 2. Does increased water intake have a beneficial effect in ADPKD patients? Recommendation Grade: C1
Human studies of high water intake to affect the progression of renal dysfunction in ADPKD patients have not been reported; however, drinking water can affect the progression of ADPKD by suppressing ADH, resulting in attenuation of cyst growth and proliferation of cystic cells. Thus, 2.5 -4 L/day of water intake would be recommended for ADPKD.

[Summary]
A 3 0 -5 0 -cyclic adenosine monophosphate (cAMP)mediating vasopressin receptor can stimulate cystic cell proliferation and fluid secretion into cysts in ADPKD. Thus, a novel treatment of ADPKD that targets the vasopressin-cAMP axis is currently evaluated and a selective inhibitor of vasopressin two receptor is adopted and examined for its effects on ADPKD. Another way to suppress vasopressin secretion is to increase fluid intake to mediate osmoregulation. Although human studies have not been reported regarding the effect of high water intake on the renal size and function of ADPKD, increasing water intake could be recommended to affect the progression of ADPKD based on the biological properties of the cystic epithelium. A larger human study is needed to clarify the effect of high water intake; patients would be advised to avoid stimulating vasopressin secretion by chronic water depletion.

CQ 3. Should we recommend dietary protein restriction (DPR) to inhibit progression of renal dysfunction in patients with ADPKD? Recommendation Grade: C1
Evidence is limited and unclear whether DPR is effective for inhibiting progression of renal dysfunction in patients with ADPKD; however, it may considered. [Summary]

CQ 1. Is antihypertensive treatment recommended as a means of slowing the deterioration of renal function in patients with ADPKD complicated with hypertension? Recommendation Grade: C1
Antihypertensive treatment is recommended for patients with ADPKD complicated with hypertension to slow the deterioration of renal function.

[Summary]
The effect of DPR on ADPKD has been examined by several clinical studies, including small retrospective studies and randomized clinical trials. However, almost all studies have shown no significant effect of DPR on the progression of renal dysfunction. Although a metaanalysis showed the efficacy of DPR in patients with CKD, including ADPKD, the effect in ADPKD patients alone was not evaluated. However, we could not conclude that DPR is ineffective for those patients because of the many limitations of those clinical studies, such as a small sample size, low prevalence of outcome due to a short observation period, and low adherence to DPR. Thus, further evidence is required to answer this question.

CQ 4. Is tolvaptan recommended for treatment of ADPKD? Recommendation Grade: B
Tolvaptan slow the increase in total kidney volume and the decline in kidney function in ADPKD patients with a relatively-good renal function with creatinine clearance C60 mL/min by Cock-Croft equation and a total kidney volume of 750 ml or more. Therefore, tolvaptan is recommended for treatment of ADPKD.

[Summary]
Tolvaptan, a V 2 -receptor antagonist, selectively blocks the binding of vasopressin to the V2-receptors and inhibit production of cAMP. To determine the effect of tolvaptan to suppress the increase in total kidney volume, a phase 3, international multicenter, doubleblind, placebo-controlled, 3-year trial (TEMPO3/4) was performed. The results of the trial demonstrated that tolvaptan slowed the increase in total kidney volume and the decline in kidney function in ADPKD patients with a relatively-good renal function with creatinine clearance C60 mL/min by Cock-Croft equation and a total kidney volume of 750 mL or more. Due to the lack of other specific and efficacious treatments for ADPKD at present time, with particular attention to serious adverse events such as drug-induced liver injury, tolvaptan is recommend for treatment of ADPKD patients with a relativelygood renal function and a total kidney volume of 750 mL or more. However, the safety of tolvaptan therapy for adult patients with creatinine clearance \60 mL/min or total kidney volume less than 750 mL or children is not established.

CQ 5. Aspiration of renal cysts in patients with ADPKD Recommendation Grade: C1
Aspiration of renal cysts for ADPKD is not recommended for improving renal function. The procedure would be considered in the management of diseaserelated chronic pain or abdominal distention, as well as for diagnostic purposes and the treatment of infected cysts.

[Summary]
A review of cyst aspiration and surgical cyst decortication for symptomatic ADPKD was performed. The impact of renal cyst aspiration or surgical cyst decortication on renal function and hypertension in patients with ADPKD is controversial, but these procedures are highly effective in the management of disease-related chronic pain. The duration of pain relief is shorter in cyst aspiration than surgical cyst decortication.
The cyst aspiration technique for simple renal cysts can be used for ADPKD. Cyst aspiration followed by instillation of a sclerosing agent (most commonly ethanol) is indicated when the symptoms are caused by one or few dominant or strategically located cysts. Cyst aspiration and sclerosis for multiple cysts need further investigation.
Cyst aspiration for diagnostic purposes and the treatment of infected cysts has been the standard procedure.

CQ 6. Does screening of intracranial aneurysms improve the prognosis of ADPKD patients? Recommendation Grade: B
The prevalence of unruptured intracranial aneurysms in ADPKD patients is higher than that in the general population. Intracranial hemorrhage, either cerebral or aneurysmal subarachnoid hemorrhage (SAH), confers high risks for mortality and morbidity in ADPKD patients. Screening of intracranial aneurysms improves prognosis.

[Summary]
The high incidence of intracranial aneurysms in patients with ADPKD has long been recognized. Rupture of an intracranial aneurysm resulting in SAH is the most devastating extrarenal complications and often results in premature death or disability. The prevalence rate of unruptured intracranial aneurysms in patients with ADPKD is higher than that in people without comorbidity. Firstdegree relatives (parents, siblings, and children) of patients with subarachnoid hemorrhage have a 3-7 times higher risk for SAH than the general population.
Aneurysm size correlates with the presence of symptoms and the risk of bleeding, and aneurysms may rupture more often and at a younger age than sporadic aneurysms. However, there is no correlation between the risk of rupture and sex, renal function and blood pressure. Hence, it is difficult to predict intracranial aneurysm rupture.
Intracranial hemorrhage, either cerebral hemorrhage or aneurysmal SAH, confers high risks for mortality and morbidity in PKD patients. Screening of intracranial aneurysms improves prognosis.

CQ 7. Is treatment recommended for cerebral aneurysms detected during screening? Recommendation Grade: C1
Treatment of a cerebral aneurysm is determined by a comprehensive examination of factors such as location, shape, and size of the aneurysm, and general conditions, age, and medical history of the patient. Decisions regarding treatment advisability and method should follow consultation with a neurosurgeon.

[Summary]
Considering that a ruptured cerebral aneurysm is a lifethreatening complication, detection of an unruptured cerebral aneurysm during screening should receive all due attention. However, there is no particular treatment for the latter, which is specific to ADPKD. Detection of a cerebral aneurysm during screening should be followed by careful control of smoking, alcohol consumption, and blood pressure. Treatment of a cerebral aneurysm is surgery, involving a craniotomy and endovascular treatment, with specifics determined following comprehensive investigation of the location, shape, and size of the aneurysm, and general conditions, age, and medical history of the patient. As treatment options have their respective strengths and weaknesses, decisions should follow consultation with a neurosurgeon. If conservative observation is chosen, biannual-or at the very least, annual-monitoring of aneurysm size is recommended.

CQ 8. Are newer quinolones recommended for the treatment of cyst infection in ADPKD? Recommendation Grade: C1
Administration of the newer quinolones is recommended for the treatment of cyst infection in ADPKD.

[Summary]
Cyst infection is a frequent and serious complication of ADPKD and is often refractory and difficult to treat. Most causative bacteria originate from the intestine, and many are gram-negative rods. Fluoroquinolones, which have broad effectiveness against gram-negative rods and good penetration of cysts, is recommended for the treatment of infected cysts in ADPKD. Having said this, however, there has not been an adequate level of study to investigate the actual effectiveness of fluoroquinolones for treating cyst infection in ADPKD. Few studies have compared fluoroquinolones with other antibiotics for the treatment of cyst infection in ADPKD.

CQ 9. Should we recommend tranexamic acid in the treatment of cystic hemorrhage in ADPKD? Recommendation Grade: C1
Tranexamic acid may be considered when cystic hemorrhage does not improve by conservative treatment.

[Summary]
Hematuria is a common problem in patients with polycystic kidney disease. It can be spontaneous or result from trauma, renal calculi, tumor, or infection. These episodes are normally managed with conservative medical treatment and rarely require surgery or embolization. Only a few published studies have investigated the use of tranexamic acid for the treatment of cystic hemorrhage in ADPKD. However, these studies demonstrated that tranexamic acid can be used safely and is effective for selected ADPKD patients with severe or intractable cystic hemorrhage that does not respond to conventional treatment.
Thus, tranexamic acid may be considered when cystic hemorrhage does not improve by conservative treatment.

CQ 10. Are there any effective pharmacological preventive therapies for urolithiasis associated with ADPKD? Recommendation Grade: C1
Because of the lack of data about the prophylactic efficacy for urolithiasis in patients with ADPKD, we cannot recommend any medical treatment to provide a prophylactic benefit. We may recommend, however, the standard prophylactic treatment in patients with metabolic disorder.

[Summary]
Renal calculi were detected in 21 % of male and 13 % of female patients with ADPKD. Anatomical urinary retention and metabolic disturbance in patients with Clin Exp Nephrol (2016) 20:493-509 501 ADPKD tend to cause development of renal stones. The main component of the stones is uric acid, and the most common metabolic abnormality is hyperoxaluria. Medical preventive treatments are not recommended because of the lack of studies that prove their efficacy. General preventive measures are recommended for fluid intake and diet.

CQ 11. Is transthoracic echocardiography (TTE) for screening of valvular disease recommended to improve the mortality of ADPKD patients? Recommendation Grade: C1
We suggest a TTE study for valvular disease only if the patients have heart murmur to evaluate the severity of valvular diseases.

[Summary]
Mitral valve prolapse and mitral regurgitation (MR) are the common cardiac complications in ADPKD. Twentyone percent of Japanese ADPKD patients have MR. However, solid data on the natural history of valvular disease in ADPKD are currently lacking, and studies with long-term follow-up periods are also very few.
According to the reports regarding non-ADPKD patients, mild or trivial MR carries better prognosis and is thought not to affect the loss of cardiac function and mortality in cardiovascular diseases.
For patients with a heart murmur, it is uncertain whether the disease is mild or severe. TTE might be useful to evaluate indications for surgical treatments and improve the mortality of these ADPKD patients.

CQ 12. Should ADPKD patients with ESRD undergo renal transarterial embolization to reduce enlarged kidneys? Recommendation Grade: C1
Renal transarterial embolization in ADPKD patients with ESRD is effective in reducing the size of enlarged kidneys and is therefore recommended.

[Summary]
As ADPKD patients age, kidney enlargement becomes increasingly pronounced, with some patients experiencing considerable abdominal bloating. Such patients are unable to eat properly, leading to malnutrition and an overall deterioration of health. However, there is no clear treatment for massively enlarged kidneys. The literature remains sparse on renal transarterial embolization in ADPKD patients with enlarged kidneys, and reports differ as to the embolism type. However, as renal transarterial embolization was demonstrated to reduce kidney swelling in all existing reports, the procedure is believed to be effective for ADPKD patients and is therefore recommended despite the paucity of evidence.

CQ 13. Should ADPKD patients with ESRD undergo hepatic transarterial embolization to reduce hepatomegaly? Recommended Grade: C1
Hepatic transarterial embolization in ADPKD patients with ESRD is effective in reducing hepatomegaly and is therefore recommended.

[Summary]
As ADPKD patients age, liver cysts proliferate and hepatomegaly becomes increasingly pronounced, with some patients experiencing extreme abdominal bloating. Such patients are unable to eat properly, leading to malnutrition and an overall deterioration of health. However, there is no clear treatment for a massively enlarged liver. There are limited reports of hepatic transarterial embolization in ADPKD patients with hepatomegaly, but they are individual or collected case reports, as opposed to scientific studies. The evidence presented in these reports is meager, but as there is some suggestion that hepatic transarterial embolization may be effective in ADPKD patients with enlarged livers, the procedure is recommended.

CQ 14. Is peritoneal dialysis recommended for patients with ADPKD? Recommended Grade: C1
Peritoneal dialysis is recommended for patients with ADPKD.
[Summary] Peritoneal dialysis is not considered appropriate or suitable in ADPKD patients because of the limited peritoneal space due to enlarged kidneys. However, according to the recent European Renal Best Practice Guidelines, initiation of dialysis with peritoneal dialysis should not be considered a contraindication. Which of the two modalities, hemodialysis or peritoneal dialysis, is better for patients' long survival? Although there have been several studies concerning this question that examined different populations and situations of dialysis patients, there is no definite conclusion or consensus on this matter. The dialysis modalities, hemodialysis or peritoneal dialysis, should be decided by patients themselves according to the suitability of the modality for the patients.

CQ 15. Is unilateral or bilateral nephrectomy recommended
during ADPKD kidney transplantation? Recommendation Grade: C1 If native kidney enlargement seems sufficiently massive to jeopardize accommodation of the donor kidney, unilateral or bilateral nephrectomy is recommended.

[Summary]
Renal transplantation for ADPKD patients proceeds routinely as it does for other patients, including incorporation of immunosuppressive therapy. Posttransplant survival is more favorable for ADPKD than for other ESRD patients. However, patients should be monitored postoperatively for possible complications such as thromboembolism, hyperlipidemia, postoperative diabetes onset, and hypertension. Careful screening is required to ensure that any kidney from a living donor is free of ADPKD. If the patient has a cerebral aneurysm, treatment is preferable prior to renal transplantation. If native kidney enlargement seems sufficiently massive to jeopardize accommodation of the donor kidney, unilateral (or rarely, bilateral) nephrectomy is recommended. However, there is no professional consensus on issues such as nephrectomy timing (simultaneous or heterochronic), scope (unilateral or bilateral), or method (open or laparoscopic).

Autosomal recessive polycystic kidney disease (ARPKD): disease concept/definition (etiology and pathophysiological mechanism)
ARPKD is a hereditary cystic kidney disease and inherited as an autosomal recessive trait. It is characterized by cystic dilation of renal collecting ducts and varying degrees of hepatic abnormalities consisting of biliary dysgenesis, and periportal fibrosis and bile duct proliferation in the liver. Generally, the hepatic lesion in ARPKD is clinically called congenital hepatic fibrosis if it presents alone, and is associated with the histological feature called ductal plate malformation. ARPKD is caused by mutations in PKHD1, located on chromosome 6p21.1-p12, and linkage analysis indicates that this disorder involves a single defective gene despite the wide variability in clinical presentation. It is found that causative gene proteins in three human PKDs (PKD1, PKD2, and ARPKD) are associated with primary cilia and the related structures, and it is inferred that structural abnormality and dysfunction of the primary cilia cause disease, and it is a theoretical rationale for the common pathophysiological mechanism of ARPKD and ADPKD. 6. ARPKD: diagnosis (symptomatology, symptom, and examination finding) Renal ultrasonographic findings and a sibling with a history of ARPKD are important for the diagnosis of ARPKD.
Cysts are usually small, and have mainly diffuse dilatations rather than a round shape. Renal ultrasonography demonstrates markedly enlarged echogenic kidneys, not a hubblebubble low-echogenic appearance, and this recognition is important for diagnosis. Sonographic features of ARPKD may manifest in the second trimester but usually are not apparent until after 30 weeks' gestation. Many diseases present with kidney cysts, all of which can be differential diagnoses. Among hereditary cystic kidney diseases, ADPKD is an important differential diagnosis. Occasionally, even in ARPKD, dilatation of the collecting ducts is not detected and macrocysts are present, which is a feature to notice. In advanced cases of ARPKD, it is sometimes difficult to morphologically distinguish ARPKD from ADPKD. Although ARPKD presents in infancy in most patients, a subset presents later in childhood and even adulthood, with abdominal distension related to renal enlargement or splenohepatomegaly. 7. ARPKD: epidemiology and prognosis (incidence, prevalence, and treatment outcome) The incidence of ARPKD is inferred to be one case per 10,000-40,000 births. Prognosis is difficult to assess, although now it becomes clear that survival of all but the most severely affected neonates who demonstrate pulmonary hypoplasia is possible. It is expected that the prognosis will be improved in the future through improvement in the treatment of end-stage renal failure and disease management in infants early after birth.

ARPKD: prenatal diagnosis
In ARPKD, considering that patients often show severe clinical features early after birth, the prenatal diagnosis is useful in disease management. Prenatal diagnosis involves fetal ultrasonography and MRI, and there is no doubt of the clinical significance of performing these diagnostic imaging methods when required in present conditions of perinatal medical care. However, the precision of imaging techniques such as ultrasonography is low, and cysts of ARPKD are usually inapparent until 30 weeks' gestation. Prenatal diagnosis of ARPKD by genetic analysis is established technically, and its enforcement is considered when a sibling is diagnosed with ARPKD. However, the request for a genetic examination from an overseas laboratory as an option may be subjected to genetic counseling because the enforcement of prenatal genetic diagnosis in Japan is difficult. 9. ARPKD: treatment and management of complications (treatment of disease including adjunct therapy, supportive therapy, and prophylaxis) Peritoneal dialysis is considered for the improvement of the vital prognosis and QOL of patients with ARPKD. Endstage renal failure is often seen in ARPKD, and a replacement therapy for the kidney is required for those cases. Generally, hemodialysis is often unsuitable for children, and peritoneal dialysis is recommended when there are no special circumstances. It is a consensus that peritoneal dialysis is recommended for the improvement of the vital prognosis and QOL of patients with ARPKD considering the present conditions in the medical care of renal failure.

CQ 17. Is solitaryor simultaneous transplantation of the liver and kidney recommended for the improvement of the vital prognosis and QOL of patients with ARPKD? Recommendation Grade: C1
Solitary or simultaneous transplantation of the liver and the kidney may be considered for the improvement of the vital prognosis and QOL of patients with ARPKD. However, its adaptation should be decided carefully according to individual cases.

[Summary]
Although solitary or simultaneous transplantation of the liver and the kidney should be considered for the improvement of the vital prognosis and QOL of patients with ARPKD, its adaptation should be decided carefully according to individual cases. In ARPKD, because patients often show severe renal failure early after birth, a replacement therapy for the kidney is required. Generally, the best replacement therapy method for the kidney in children is thought to be renal transplantation, and its early enforcement is recommended. When the management of portal hypertension or recurrent bacterial cholangitis is difficult in the case of liver disorder in ARPKD patients, liver transplantation is considered. Although solitary or simultaneous transplantation of the liver and kidney should be considered for the improvement of the vital prognosis and QOL of patients with ARPKD considering the present conditions of transplantation medical care, its enforcement does not necessarily result in the improvement of vital prognosis and QOL in each case. CQ 18. Is antihypertensive therapy recommended for the improvement of the vital prognosis of patients with ARPKD? Recommendation Grade: C1 Antihypertensive therapy improves the vital prognosis of patients with ARPKD.

[Summary]
Antihypertensive therapy improves the vital prognosis of patients with ARPKD. Therefore, it may be considered a management option for ARPKD. Hypertension is often found in infants and subsequent childhood in ARPKD, and it can be the only symptom. Hypertension is also seen in patients with normal renal function and is manifested in almost all children with ARPKD. If hypertension is not treated effectively, hypercardia or congestive heart disorder may occur. The pathogenesis of hypertension in ARPKD is unknown. It is a consensus that antihypertensive therapy should be considered for the improvement of the vital prognosis of patients with ARPKD.

Complications and their managements
(1) Cerebral aneurysm and subarachnoid hemorrhage CQ 6:Does screening of intracranial aneurysms improve the prognosis of ADPKD patients?