What are the differences in the outcome of laparoscopic axial (I) versus paraesophageal (II–IV) hiatal hernia repair?

Introduction Comparison of elective laparoscopic repair of axial vs paraesophageal hiatal hernias reveals relevant differences in both the patient collectives and the complexity of the procedures. Materials and methods The present uni- and multivariable analysis of data from the Herniamed Registry compares the outcome for 2047 (67.3%) (type I) axial with 996 (32.7%) (types II–IV) paraesophageal primary hiatal hernias following laparoscopic repair. Results Compared with the patients with axial hiatal hernias, patients with paraesophageal hiatal hernia were nine years older, had a higher ASA score (ASA III/IV: 34.8 vs 13.7%; p < 0.001), and more often at least one risk factor (38.8 vs 21.4%; p < 0.001). This led in the univariable analysis to significantly more general postoperative complications (6.0 vs 3.0%; p < 0.001). Reflecting the greater complexity of the procedures used for laparoscopic repair of paraesophageal hiatal hernias, significantly higher intraoperative organ injury rates (3.7 vs 2.3%; p = 0.033) and higher postoperative complication-related reoperation rates (2.1 vs 1.1%; p = 0.032) were identified. Univariable analysis did not reveal any significant differences in the recurrence and pain rates on one-year follow-up. Multivariable analysis did not find any evidence that the use of a mesh had a significant influence on the recurrence rate. Conclusion Surgical repair of paraesophageal hiatal hernia calls for an experienced surgeon as well as for corresponding intensive medicine competence because of the higher risks of general and surgical postoperative complications.

which may result in an ''upside-down stomach'' [1]. Patients with an axial/sliding or type I hernia and long-term treatment of gastroesophageal reflux disease and continuous reduced quality of life, persistent troublesome symptoms, and/or progression of disease despite adequate proton pump inhibitor therapy in dosage and intake are the best candidates for surgery [2]. Although paraesophageal hernias types II-IV account for only 5% of all hiatal Fig. 1 Flowchart of patient inclusion hernias, their detection is important because of potentially life-threatening complications, such as obstruction, acute dilatation, perforation, or bleeding of the stomach mucosa [1]. In essence, no conventional options are available for the treatment of paraesophageal hernia, so surgical repair is recommended for relief of symptoms [1].
Laparoscopic hiatal hernia repair is as effective as open transabdominal repair, with a reduced rate of perioperative morbidity and with shorter hospital stays. It is the preferred approach for the majority of hiatal hernias [3][4][5][6]. Laparoscopic posterior fundoplication is given preference over laparoscopic anterior fundoplication due to a lower recurrence rate [7] in the treatment of gastroesophageal reflux disease. Thirteen randomized controlled trials with 1564 patients showed for Toupet versus Nissen fundoplication significantly lower rates of adverse results involving dysphagia, gas-bloat syndrome, inability to belch, and reoperation due to severe dysphagia [8,9]. Mesh application should be considered for large hiatal hernia repair because it reduces recurrences, at least in the midterm. Overall, procedure-related complications and mortality do not seem to be increased despite potential mesh-associated complications [10][11][12][13][14][15][16][17].
In the literature, there is only one publication with a large case series which compares the patient collective, treatment, and the outcome of laparoscopic repair of type I hiatal hernias with those of paraesophageal hiatal hernias (types II-IV) [18]. In that study, most of the complications occurred in patients with paraesophageal compared with axial hernia (10 vs 1%, respectively) [18]. This variation reflects significant differences between patients with axial hiatal hernia, and gastroesophageal reflux disease, and those with paraesophageal hernia; it also highlights the increased complexity of the laparoscopic repair procedure used for paraesophageal hernia [18]. Based on data from the Herniamed Hernia Registry, this paper now explores the differences between these patients in terms of demographic characteristics, treatment, and outcome.

Materials and methods
The Herniamed quality assurance study is a multicenter, internet-based hernia register [19] into which 577 participating hospitals and surgeons engaged in private practice (Herniamed Study Group) in Germany, Austria, and Switzerland (status: October 10, 2016) have entered data prospectively on their patients who had undergone routine surgery and signed an informed consent agreeing to participate. As part of the information provided to patients regarding participation in the Herniamed Quality Assurance Study, all patients are informed that the treating hospital would like to be informed about any problems occurring after the operation and that the patient has the opportunity to attend for clinical examination. All postoperative complications occurring up to 30 days after surgery are recorded. On one-year follow-up, postoperative complications are once again reviewed when the general practitioners and patients complete a questionnaire. On one-year follow-up, general practitioners and patients are also asked about any recurrent symptoms, pain at rest, pain on exertion, and chronic pain requiring treatment. If recurrent symptoms or chronic pain are reported by the general practitioners or patients, patients can be requested to attend for clinical examination or radiologic tests. A recent publication has provided impressive evidence of the role of patient-reported outcomes in hernia surgery [20]. The present analysis compares the prospective data collected for all patients with a hiatal hernia (types I-IV) and laparoscopic repair. Inclusion criteria were minimum age of 16 years, primary elective laparoscopic operation, fundoplication or fundophrenicopexy, and availability of data on one-year follow-up. In total, 3043 patients were enrolled from 197 participating institutions with mean number of 15.4 (range 1-199) cases between September 1, 2009 andSeptember 1, 2015 (Fig. 1). Of these patients, 2047 (67.3%) had an axial/sliding (type I) and 996 (32.7%) a paraesophageal (types II-IV) hiatal hernia (Table 1). No details of the diagnostic method used for classification of hernia type were included in the registry. The demographic parameters included age (years), gender, symptoms, ASA score (I, II, III, IV), body mass index (BMI) (kg/m 2 ), and risk factors (COPD, diabetes, aneurysms, cortisone, immunosuppression, etc.). Risk factors were dichotomized, i.e., ''yes'' if a risk factor was positive and ''no'' otherwise.
The second group of categorical influence variables reflecting surgery-related parameters included defect size, operation technique (Toupet vs Nissen vs fundophrenicopexy), and hiatoplasty (suture vs mesh vs suture and mesh).
The dependent variables were intra-and postoperative complication rates, complication-related reoperation rates, recurrence rates and rates of pain at rest, pain on exertion, and chronic pain requiring treatment.
All analyses were performed with the software SAS 9.4 (SAS Institute Inc. Cary, NC, USA) and intentionally calculated to a full significance level of 5%, i.e., they were not corrected in respect of multiple tests, and each p value B0.05 represents a significant result. To discern differences between the groups in unadjusted analyses, Fisher's exact To access influence factors in multivariable analyses, the binary logistic regression model for dichotomous outcome variables was used. Estimates for odds ratio (OR) and the corresponding 95% confidence interval based on the Wald test were given. For influence variables with more than two categories, all pairwise odds ratios were given. For age (years), the 10-year OR estimate, for BMI (kg/m 2 ), the five-point OR, and, for defect size, the ten-point OR estimate were given. For the procedure time (min) and hernia defect size (cm 2 ), a logarithmic transformation was applied and re-transformed mean values and ranges specified. The results of multivariable analyses are presented in tabular form, sorted by descending impact.

Univariable analyses
Patients with axial hiatal hernia (type I) and reflux disease compared with patients with paraesophageal hiatal hernia (types II-IV) were on average more than nine years younger, had a somewhat lower BMI, markedly shorter procedure time, and smaller hernia defects ( Table 2).
Besides, the proportion of patients with at least one risk factor was significantly higher for paraesophageal hernias at 30.8 vs 21.4% (p \ 0.001). In terms of symptoms, only reflux (89.3 vs 66.0%; p \ 0.001) was more common for axial hiatal hernias (Table 3).
On overall assessment of the intraoperative complication rates no difference was detected between the axial (type I) and paraesophageal hiatal hernias (types II-IV) ( Table 4). However, organ injuries were seen significantly more often with paraesophageal hiatal hernias (types II-IV) (3.7 vs 2.3%; p = 0.033).
As regards the postoperative surgical complications, no significant difference was detected between the axial (type I) and paraesophageal hiatal hernias (types II-IV). However, more complication-related reoperations (Clavien-Dindo classification grade III) were noted for paraesophageal compared with axial hernias (2.1 vs 1.1%; p = 0.032) ( Table 4). The main reasons for this were esophageal and gastric injuries, secondary bleeding, and abscesses.
For the general postoperative complications, a highly significant difference to the disadvantage of the paraesophageal hernias (types II-IV) was detected at 6.0 vs 3.0% (p \ 0.001) ( Table 4). Since one-year follow-up was a precondition for patient selection, analysis did not take account of deaths. In the hiatal hernia operation group up to 1 September, 2015, including among patients without oneyear follow-up (n = 1.086) (Fig. 1), one death occurred in the axial (type I) hiatal hernia group (one out of 2792; 0.04%) and three deaths in the paraesophageal (types II-IV) group (three out of 1.333; 0.22%).
On one-year follow-up, no significant difference was identified in the recurrence rate or in the rates of pain at rest, on exertion or requiring treatment (Table 4). An additional analysis of patient outcome in relation to the individual hospital's case load showed no significant differences for a case load of 1-49, 50-99, and C100 (Table 5).

Intraoperative complications
The results of the model used for analysis of influencing factors for intraoperative complications are illustrated

Surgical postoperative complications
Model matching for analysis of the postoperative complications, which reflects the suitability of the influence    parameters to explain the outcome variable scores, was not significant (p = 0.335). As such, there was no evidence of the individual variables having significantly influenced the postoperative complication rate.

Complication-related reoperations
Model matching for complication-related reoperations, which reflects the suitability of the influence parameters to explain the outcome variable scores, was not significant (p = 0.249). As such, there was no evidence of the individual variables having significantly influenced the complication-related reoperation rate.

General postoperative complications
The results of the model used for analysis of the general postoperative complication rate are shown in Fig. 3

Recurrence on one-year follow-up
Model matching for recurrence on one-year follow-up, which reflects the suitability of the influence parameters to explain the outcome variable scores, was not significant (p = 0.180). As such, there was no evidence of the

Pain on exertion on follow-up
Model matching for pain on exertion on one-year followup, which reflects the suitability of the influence parameters to explain the outcome variable scores, was not significant (p = 0.154). As such, there was no evidence of the individual variables having significantly influenced the pain on exertion rate.

Chronic pain requiring treatment on one-year follow-up
The results of the model used for analysis of chronic pain requiring treatment are summarized subsequently (model

Discussion
This paper analyzes prospective data from the Herniamed Registry for 3043 patients with primary, elective, and laparoscopic repair of a hiatal hernia. Only patients with complete one-year follow-up results were included in the analysis. Since the outcome for patients with axial hiatal hernia and reflux disease differs greatly from that of patients with paraesophageal hiatal hernia, due to divergent patient characteristics and complexity of the repair technique, the two patient collectives were compared in the analysis presented here. First of all, significant differences were noted in the patient characteristics. Patients with paraesophageal hernia were on average almost 10 years older, had a somewhat higher BMI, larger hernia defect, and tended more often to be female. The chief determinant for onset of significantly more perioperative complications among patients with paraesophageal hiatal hernia was a higher proportion of patients with ASA scores III/IV (34.8 vs 13.7%; p \ 0.0001) and of patients with risk factors (30.8 vs 21.4%; p \ 0.001).
Both these factors help to explain the significantly more frequent onset of general postoperative complications after repair of paraesophageal compared with axial hiatal hernias (6.0 vs 3.0%; p \ 0.001). Multivariable analysis clearly demonstrates that the presence of at least one risk factor and higher age significantly increases the risk of general postoperative complications.
The greater complexity of the procedures used for paraesophageal hiatal hernia repair is reflected in a significantly higher intraoperative organ injury rate (3.7 vs 2.3%; p = 0.033) and significantly higher rate of complication-related reoperations (2.1 vs 1.1%; p = 0.033) compared with axial hiatal hernias.
The recurrence rate on one-year follow-up for patients after laparoscopic repair of axial hiatal hernias was 5.1% and for paraesophageal hiatal hernias it was 4.0% (p = 0.204), with the proportion of mesh-augmented hiatoplasties being significantly higher (35.2 vs 17.7%; p \ 0.001) for paraesophageal hiatal hernias. The indication for mesh use was decided by the individual surgeon or hospital. The specific reasons for using a mesh were not documented.
Multivariable analysis did not find any evidence that the use of a mesh or other factors had a significant influence on the recurrence rate on one-year follow-up. That concords with the meta-analysis of four randomized controlled trials with 406 patients by Memom et al. [16]. It can only be speculated whether the significantly more frequent use of meshes for types II-IV hiatal hernias with highly significantly larger hiatal defects had led to a non-significant difference in the recurrence rate. In less than 1% of cases, only a mesh and no suture was used for hiatal closure, as reported in the literature [21]. That practice is not recommended in the guidelines [4].
There was no significant difference in the rates of pain at rest, pain on exertion, or pain requiring treatment on oneyear follow-up between the patients after laparoscopic repair of axial (type I) vs paraesophageal (types II-IV) hiatal hernia.
Multivariable analysis demonstrates that the risk of pain at rest and pain requiring treatment was higher in the presence of risk factors, and was lower among men and in patients with higher BMI.
In summary, patients with elective laparoscopic repair of primary paraesophageal (types II-IV) vs axial (type I) hiatal hernia were found to have a significantly higher risk of general postoperative complications because of higher age and higher ASA score as well as the higher proportion of patients with at least one risk factor. Reflecting the greater complexity of laparoscopic paraesophageal (types II-IV) hiatal hernia repair procedures, there is greater likelihood of significantly more intraoperative organ injuries and postoperative complication-related reoperations. Accordingly, laparoscopic procedures for repair of paraesophageal (types II-IV) hiatal hernias should only be undertaken by experienced surgeons. Because of the higher risk of general postoperative complications, corresponding intensive medicine resources are needed.