Medical and economic consequences of perioperative complications in older hip fracture patients

Summary Patients suffering from complications during inpatient treatment after hip fracture surgery are associated with a worse mid-term outcome. While surgically treatable complications only delay the healing process, internal complications seem to worsen the outcome in the long run. All complications come with significant increased costs during the hospital stay. Purpose Due to the demographic changes, the importance of hip fractures is still increasing nowadays. Not only surgical but also medical complications represent a major challenge in the treatment of those patients. Nevertheless, only few is known about the functional, medical, and economic consequences of complications. Methods A total of 402 hip fracture patients ≥ 60 years were observed prospectively at a German university hospital. Complications were assessed during the inpatient stay and classified by Clavien and Dindo. Afterwards their influence on acute care costs was examined as well as their influence on the mortality, health-related quality of life (HRQL) (EQ5D), functional capacities (Barthel index), and mobility (Tinetti score) in the follow-up periods of 6 and 12 months. Results Complications that required surgical revision/treatment (type III) were associated with an increased 6 months’ mortality, while type II and IV complications did not influence mortality after 6 and 12 months. Six months after surgery, HRQL, Barthel score, and Tinetti score were reduced in patients suffering from all different types of complications. After 12 months however, HRQL, Barthel score, and Tinetti score following type II and IV complications remained reduced, while the scores improved in patients suffering from type III complication. All types of complications led to significantly increased acute care costs. Conclusions The results of the present study emphasize the crucial role of perioperative complications in older patients with hip fractures. Therefore, special attention has to be given to the prevention of those complications, e.g., with orthogeriatric treatment models, which have been shown to be effective in the reduction of complications.


Introduction
Due to the demographic changes, the treatment of geriatric patients is gaining more attention nowadays. Hip fractures represent typical fragility fractures and their incidence is still rising [1][2][3]. A worldwide increase in hip fractures from 1.7 million in 1990 to 6.3 million by 2050 has been estimated by Cooper et al. [4]. The co-existence of relevant co-morbidities, polypharmacy, cognitive impairment, and impaired mobility results in high rates of complications in this vulnerable population [5,6].
Complication rates around 20-75% have been described in the literature with most of the complications being not directly associated with the surgical procedure [5,[7][8][9][10][11][12]. Surgical complications account for only 6.9%, mechanical failure and infection being the most common ones [7]. However, medical but not surgical complications have been shown to be associated with increased mortality [7,13].

Patients and treatment parameters
The present study is a sub-analysis of a prospective observational study including a total of 402 patients with hip fractures treated between April 2009 and October 2011. Patients ≥ 60 years with operative treatment due to hip fractures were included. Exclusion criteria were malignancy-related fractures and polytrauma patients (ISS ≥ 16 [19]). Five hundred thirtynine patients with fracture were treated at our hospital during the observation period. Four hundred seventy-seven patients met the inclusion criteria. Of those 477 patients, 75 patients declined participation. We obtained approval by the local Ethics committee (AZ 175/08). Each patient or their legal guardians provided written informed consent for participation in the study. Mortality, clinical course, treatment costs, and short-term follow-up are already published in some publications of our study group [13,[20][21][22].
The following data were collected during time of hospitalization: time to surgery (≤ 24 h vs. > 24 h), surgical procedure (screw fixation, intramedullary nail, dynamic hip screw, hemiarthroplasty, and total hip arthroplasty), ICU readmission after surgery, transfusion of erythrocyte concentrates, and duration of stay at the acute-care hospital. Follow-up was obtained after 6 months and 1 year. EQ5D-5L [26], Barthel score [27], and Tinetti score [28] were collected during the different follow-up examinations. The Barthel Score (range 0-100 points) records essential everyday functions of the patients. Patients are divided into independent, partially independent, needy and largely dependent on care. The Tinetti score (range 0-28 points) is divided into 2 parts, a balance test and a walking test. The Tinetti score can be used to quantify the fall risk of the patient. Both tests are established screening tools in the treatment of geriatric patients. Complications were assessed during the inpatient stay and classified by Clavien and Dindo. The current classification is an update of the previous classification by Clavien in 1992. It was published in 2004 by Dindo et al. Grade 1 complication represents any deviation from the normal without the need of pharmacological treatment (except for antiemetics, antipyretics, analgetics, diuretics, electrolytes, and physiotherapy) or surgical, endoscopic, and radiological interventions. This includes for example transient elevation of the serum creatinine, atelectasis requiring physiotherapy, and noninfectious diarrhea. Grade 2 complication stands for a pharmacological treatment with drugs other than such allowed in grade 1, for example tachyarrhythmia requiring β-receptor antagonist, pneumonia, and urinary tract infections treated with antibiotics. Grade 3 complications require surgical, endoscopic, or radiological intervention like wound infection with the need of surgical intervention with the need of an anesthesia or pleural effusion with the need of a pleura drainage. Life-threatening complications are defined as grade 4 complications This includes for example acute renal failure requiring dialysis lung failure requiring intubation [29].

Costs for acute inpatient treatment
The methodology regarding the calculation of the costs that has already been described in a prior study of our group [30]. All potential cost factors were recorded as accurately as possible for each of the 402 patients individually. Afterwards, the actual costs for each cost factor were retrospectively calculated with help of the controlling division in our financial department. For each patient, up to 196 individual parameters were recorded [30].

Data management and analysis
Data were collected in a FileMaker® database (FileMaker Inc., Santa Clara, CA, USA). We performed double entry with a plausibility check to monitor data quality. IBM SPSS Statistics 24 (Statistical Package for the Social Sciences, IBM Corporation, Armonk, NY, USA) was used for statistical analysis. To identify possible influencing factors, bivariate analysis was conducted using Student's t test or ANOVA. Statistical significance was assumed at p < 0.05. Finally, multivariate analysis with backward selection was performed to detect independent influencing factors (inclusion at p < 0.05, exclusion at p > 0.10).

Results
A total of 402 patients (293 women and 109 men) with an average age of 81.3 years (95% confidence interval (CI) 80.5-82.1) were included in the study. Baseline characteristics are shown in Table 1.

Influence of complications on mortality
The mortality of patients without complications was 13.7% in the 6 months' follow-up and 22.3% in the 12 months' followup. Patients suffering from type III complications had a significant higher mortality (27.7%; p = 0.018) after 6 months compared to patients not suffering from any of these complications. In the 12 months' follow-up, this trend could be detected as well (35.9%), however without statistical significance (p = 0.072). Complications type II and IV according to Clavien and Dindo showed no significant influence on mortality after 6 or 12 months ( Table 2).

Treatment costs: distribution and influence of complications
The average costs for overall acute-care treatment were 8853 €. All types of complications resulted in significantly higher   (Fig. 1).

Discussion
The aims of this study were to evaluate the influence of complications in older patients with hip fractures on mortality, health-related quality of life (HRQL) (EQ-5D), functional capabilities (Barthel score), mobility (Tinetti score), and their economical acute care costs.

Influence of complications on mortality
Several authors investigated mortality after hip fractures in older patients. Most of these studies focused on patients' characteristics and data from hospitalization. Usually postoperative complications were not investigated. ASA-Score [31,32], comorbidities [31,33], duration of postoperative immobilization [31], gender [32][33][34], age [32,33], and surgical delay [32] have been shown to significantly increase mortality after hip fracture. In this study, predominantly type III complications increased mortality. This underlines that mainly those complications requiring surgical revision seem to increase the risk of dying in a 12-month follow-up after surgical fixation of hip fractures.

Influence of complications on HRQL
Although several studies investigated the influence of hip fractures on quality of life, to the best of our knowledge few have included the influence of complications. Alexiou et al. showed in a review that the majority of those patients did not regain their pre-fracture quality of life [35]. Reviewing 49 studies, they stated comorbidities, female gender, and undernutrition as factors associated with a negative impact on health-related quality of life. These factors also lead to longer duration of hospital stay, severe postoperative pain, and complications [35]. Taking a closer look at the occurrence of complications, all types resulted in a significantly lower EQ-5D 6 months after the fracture. No statistically significant

Influence of complications on functional capabilities
Patients suffering from type II and type IV complications had a significantly lower Barthel score 6 and 12 months after surgery. Patients suffering from type III complications showed a trend to a lower Barthel score 6 months after surgery, which was not significant. However, they almost regained their functional capabilities after 12 months compared to patients without any complications. The additional surgery seems to prolong functional recovery of those patients, but they are not significantly affected at the 1-year follow-up. In contrast, type II and type IV complications may represent a surrogate parameter for the frailty of the patients like mentioned already above. Several authors investigated functional outcome after hip fracture. Most of them focused on patients' characteristics and data from hospitalization but did not examine the influence of different types of complications on the mid-term outcome. In the recent literature, inconsistent results have been published by different authors. This might be due to the different study collectives and study protocols. Patient characteristics that have been associated with poor functional outcome by many authors are increased age [37][38][39][40], poor mental status [37,39,41,42], and higher degree of comorbidity [38]. While there are now contradictory statements about high age alone as a risk factor, there is agreement about the influence of the previous state of health [43].
Influence of complications on mobility "Tinetti score" was used to illustrate the influence of complications on mobility after hip fracture. All types of complications lead to a significantly lower Tinetti score compared to patients not suffering from complications 6 months after the surgery. Similar to HRQL and functional status patients with type III complications improved after 12 months, whereas type II and IV complications were associated with a significantly reduced Tinetti score also after 12 months. Again, a possible explanation could be that patients suffering from surgical complications require a couple more months for

Economical acute care consequences
Our group already showed that ASA-Score, Charlson Comorbidity Index, and fracture location are influencing factors that lead to increased costs of acute care for hip fracture treatment [30]. Complications during in-hospital treatment do not only have an impact on patient's mobility, mortality, functional capability, and health-related quality of life; they go along with significantly increased acute care costs as well.
Broderick et al. showed in their selective review regarding failure of geriatric fractures that implant failure does not only lead to a twofold increase in length of stay, but leads to a doubling of healthcare costs as well [44]. Other authors showed increased costs after implant failure, wound infection, others reasons of reoperations, and medical complications [17,18,44,45]. In line with these findings, type III complications were associated with increased costs in the present study. However, patients who needed surgical revision were not those causing the highest costs in our study sample. Patients suffering from type IV complications were associated with the highest healthcare costs. This might be due to prolonged intensive care treatment and the necessary intensive inpatient treatment after suffering from these complications (e.g., dialysis). As expected, type III complications increase healthcare costs in a significant amount. Even type II complications increase healthcare costs during inpatient treatment significantly. This is explained by an extra amount of medical or personal capacities (e.g., drugs like antibiotics) required by patients suffering from type II complications.

Strengths and limitations
The results of the present study are limited by some factors. We included only patients from one single center, and only selected parameters were collected and analyzed. The fact that orthogeriatric treatment, which has been proven to be effective in reducing complications, was not performed in the present analysis represents another limitation. Furthermore, a cost analysis, regardless of how detailed and accurate it is, contains some assumptions. For example, it is not possible to exactly determine the duration of physician or nurse-patient contact during the acute ward phase. Another drawback of this study is that it only includes primary hospitalization costs. Finally, the age restriction ≥ 60 years has to be mentioned as a limitation, as this is not the typical definition of a geriatric patient and therefore non-geriatric patients may have been included. Nevertheless, the prospective design and its large patient collective are strengths of this study. Furthermore, the cost analysis represents the result of an extremely detailed analysis of the actual costs of care for every individual patient.

Conclusion
Complications after hip fracture treatment do not only increase acute care costs, but also represent a burden for those patients during the following rehabilitation. Complications that require a surgical revision/ treatment (type III) increase acute care costs as well as 6-month mortality significantly. However, once survived, type III complications are not associated with reduced HRQL, decreased functional capacities, or impaired mobility after 12 months. Nevertheless, rehabilitation seems delayed as these patients show reduced HRQL, functional capacities, and mobility after 6 months.
In contrast, type II and type IV complications are not associated with increased mortality after 6 and 12 months. However, most probably being a surrogate parameter for frailty, they are associated with reduced HRQL, reduced functional outcomes, and impaired mobility after 6 and 12 months. The results of the present study emphasize the crucial role of perioperative complications in geriatric patients with hip fractures from a medical as well as from an economic perspective. Therefore, special attention has to be given to the prevention of those complications.
Authors' contributions TK did the statistical evaluation, drafted the manuscript, and is the corresponding author. JH conceived of the study and participated in its design and coordination. JB participated in its design and coordination and helped to draft the manuscript. CS helped to draft the manuscript. CS carried out the study and helped to draft the manuscript. BB collected the data and participated in the studies' design and coordination. SR conceived of the study and participated in its design and coordination and helped to draft the manuscript. DE participated in its design and coordination and helped to draft the manuscript. RA conceived of the study, did the statistical evaluation, and participated in its design and coordination; carried out the study; and helped to draft the manuscript.
The authors declare as well that the manuscript has been read and approved by all the authors.
Funding Open Access funding enabled and organized by Projekt DEAL.
Availability of data and material Not applicable.
Ethics approval Ethical Vote was obtained from the ethics commission at the university of Marburg.
Consent to participate Written consent to participation has been obtained from all patients.

Consent for publication
No personal data, which can be assigned to a person, will be published. For this type of study, formal consent is not required.
Code availability Not applicable.
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