Modeling the volume-effectiveness relationship in the case of hip fracture treatment in Finland

Effect of institution volume on mortality and outcomes in osteoporotic hip fracture care

Hospitals that treat more patients with osteoporotic hip fractures do not generally have better care outcomes than those that treat fewer hip fracture patients. Institutions that do look after more such patients tend, however, to more consistently perform relevant health assessments.

INTRODUCTION

An inveterate link has been found between institution case volume and a wide range of clinical outcomes; for a host of medical and surgical conditions. Hip fracture patients, notwithstanding the significance of this injury, have largely been overlooked with regard to this important evaluation.

METHODS

We used the UK National Hip Fracture database to determine the effect of institution hip fracture case volume on hip fracture healthcare outcomes in 2019. Using logistic regression for each healthcare outcome, we compared the best performing 50 units with the poorest performing 50 institutions to determine if the unit volume was associated with performance in each particular outcome.

RESULTS

There were 175 institutions with included 67,673 patients involved. The number of hip fractures between units ranged from 86 to 952. Larger units tendered to perform health assessments more consistently and mobilise patients more expeditiously post-operatively. However, patients treated at large institutions did not have any shorter lengths of stay. With regard to most other outcomes there was no association between the unit number of cases and performance; notably mortality, compliance with best practice tariff, time to surgery, the proportion of eligible patients undergoing total hip arthroplasty, length of stay delirium risk and pressure sore risk.

CONCLUSIONS

There is no relationship between unit volume and the majority of health care outcomes. It would seem that larger institutions tend to perform better at parameters that are dependent upon personnel numbers. However, where the outcome is contingent, even partially, on physical infrastructure capacity, there was no difference between larger and smaller units.

Association between hospital surgical volume and complications after total hip arthroplasty in femoral neck fracture: A propensity score-matched cohort study

BACKGROUND

For displaced femoral neck fractures (FNF), total hip arthroplasty (THA) or hemiarthroplasty (HA) is preferred rather than fracture fixation. THA for patients with FNF requires skilled operators since patient with FNF likely to have osteoporosis and a higher risk of complications. Several reports suggest that higher hospital surgical volume was associated with a lower risk of complications after THA for osteoarthritis. However, little is known concerning this association with THA for FNF. Herein, we investigated the association between THA and complication and the recovery of physical function after THA to optimize the quality of FNF.

METHODS

A nationwide retrospective cohort study of elderly undergoing THA between April 1, 2011, to March 31, 2018 was performed. The association between hospital surgical volume and complication after THA for FNF was visually described with the restricted cubic spline regression analysis. Then the risk of complications was quantified with propensity score matching analysis based on the cutoff point identified by the restricted cubic spline curve. Primary outcome was secondary revision surgery, and the secondary outcomes included surgical and systemic complications, and the recovery of physical function at hospital discharge.

RESULTS

By visualization of the spline curve, we identified 20 cases per year as cutoff point of low hospital surgical volume. Following 1,396 patients' propensity score-match analysis (mean age 75.2 [SD] 8.8, female 80.4%), the risk of secondary revision surgery was significantly higher among the low hospital surgical volume group (absolute risk difference (RD), 2.44%; p = 0.011). Also, the incidence of blood transfusion was higher in the low hospital surgical volume group (RD, 4.01%; p = 0.049). However, there was no significant difference in the recovery of the transferring and walking ability at discharge between high and low hospital surgical volume groups (63.5% vs 62.6%, 58.5% vs 57.5%; p = 0.74, 0.71, respectively).

CONCLUSION

Our research demonstrated that an increase in hospital surgical volume significantly reduced the incidence of secondary revision surgery after a certain inflection point, but not significantly improved short-term physical functions.

What works? The association of organisational structure, reforms and interventions on efficiency in treating hip fractures

Many studies indicate huge regional and hospital-level differences in health care performance. In order to increase health system efficiency, it is important to know the reasons behind the differences and analyse the effects of those factors that can be affected by health policy. The aim of this study is to evaluate and compare various organisational factors and health policy interventions in the performance of the care of hip fracture patients in Finland. We analysed the relationship between organisational factors (hospital volume, regional concentration of treatments) and performance. The focus is also on the effects of two macro-level organisational changes (integration of production of all health and social services in one provider) and two micro-level interventions (integrated patient pathway interventions, aiming to discharge patients as soon as possible). Our results indicate that macro-level integration of the production or financing of health and social services, bigger hospital volumes, and the concentration of the acute phase of care in fewer hospitals within hospital districts were not consistently related to efficiency in the care of hip fracture patients. Instead, efficiency can be increased using micro-level interventions aiming to coordinate patient pathways at the patient group level.

Influence of trends in hospital volume over time on patient outcomes for high-risk surgery

BACKGROUND

The "practice makes perfect" concept considers the more frequent a hospital performs a procedure, the better the outcome of the procedure. We aimed to study this concept by investigating whether patient outcomes improve in hospitals with a significantly increased volume of high-risk surgery over time and whether a learning effect existed at the individual hospital level.

METHODS

We included all patients who underwent one of 10 digestive, cardiovascular and orthopaedic procedures between 2010 and 2014 from the French nationwide hospitals database. For each procedure, we identified three groups of hospitals according to volume trend (increased, decreased, or no change). In-hospital mortality, reoperation, and unplanned hospital readmission within 30 days were compared between groups using Cox regressions, taking into account clustering of patients within hospitals and potential confounders. Individual hospital learning effect was investigated by considering the interaction between hospital groups and procedure year.

RESULTS

Over 5 years, 759,928 patients from 694 hospitals were analysed. Patients' mortality in hospitals with procedure volume increase or decrease over time did not clearly differ from those in hospitals with unchanged volume across the studied procedures (e.g., Hazard Ratios [95%] of 1.04 [0.93-1.17] and 1.08 [0.97-1.21] respectively for colectomy). Furthermore, patient outcomes did not improve or deteriorate in hospitals with increased or decreased volume of procedures over time (e.g., 1.01 [0.95-1.08] and 0.99 [0.92-1.05] respectively for colectomy).

CONCLUSIONS

Trend in hospital volume over time did not appear to influence patient outcomes based on real-world data.

TRIAL REGISTRATION

NCT02788331, June 2, 2016.

The volume-outcome relationship for hip fractures: a systematic review and meta-analysis of 2,023,469 patients

Background and purpose - It has been hypothesized that hospitals and surgeons with high caseloads of hip fracture patients have better outcomes, but empirical studies have reported contradictory results. This systematic review and meta-analysis evaluates the volume-outcome relationship among patients with hip fracture patients. Methods - A search of different databases was performed up to February 2018. Selection of relevant studies, data extraction, and critical appraisal of the methodological quality was performed by 2 independent reviewers. A random-effects meta-analysis using studies with comparative cut-offs was performed to estimate the effect of hospital and surgeon volume on outcome, defined as in-hospital mortality and postoperative complications. Results - 24 studies comprising 2,023,469 patients were included. Overall, the quality was reasonable. 11 studies reported better health outcomes in high-volume centers and 2 studies reported better health outcomes in low-volume centers. In the meta-analysis of 11 studies there was a statistically non-significant association between higher hospital volume and both lower in-hospital mortality (adjusted odds ratio (aOR) 0.87, 95% confidence interval (CI) 0.73-1.04) and fewer postoperative complications (aOR 0.87, CI 0.75-1.02). Four studies on surgeon volume were included in the meta-analysis and showed a minor association between higher surgeon volume and in-hospital mortality (aOR 0.92, CI 0.76-1.12). Interpretation - This systematic review and meta-analysis did not find an evident effect of hospital or surgeon volume on health outcomes. Future research without volume cut-offs is needed to examine whether a true volume-outcome relationship exists.

Developing a multidisciplinary rehabilitation package following hip fracture and testing in a randomised feasibility study: Fracture in the Elderly Multidisciplinary Rehabilitation (FEMuR)

BACKGROUND

Proximal femoral fracture is a major health problem in old age, with annual UK health and social care costs of £2.3B. Rehabilitation has the potential to maximise functional recovery and maintain independent living, but evidence of clinical effectiveness and cost-effectiveness is lacking.

OBJECTIVES

To develop an enhanced community-based rehabilitation package following surgical treatment for proximal femoral fracture and to assess acceptability and feasibility for a future definitive randomised controlled trial (RCT) and economic evaluation.

DESIGN

Phase I - realist review, survey and focus groups to develop the rehabilitation package. Phase II - parallel-group, randomised (using a dynamic adaptive algorithm) feasibility study with focus groups and an anonymised cohort study.

SETTING

Recruitment was from orthopaedic wards of three acute hospitals in the Betsi Cadwaladr University Health Board, North Wales. The intervention was delivered in the community following hospital discharge.

PARTICIPANTS

Older adults (aged ≥ 65 years) who had received surgical treatment for hip fracture, lived independently prior to fracture, had mental capacity (assessed by the clinical team) and received rehabilitation in the North Wales area.

INTERVENTIONS

Participants received usual care (control) or usual care plus an enhanced rehabilitation package (intervention). Usual care was variable and consisted of multidisciplinary rehabilitation delivered by the acute hospital, community hospital and community services depending on need and availability. The intervention was designed to enhance rehabilitation by improving patients' self-efficacy and increasing the amount and quality of patients' practice of physical exercise and activities of daily living. It consisted of a patient-held information workbook, a goal-setting diary and six additional therapy sessions.

MAIN OUTCOME MEASURES

The primary outcome measure was the Barthel Activities of Daily Living (BADL) index. The secondary outcome measures included the Nottingham Extended Activities of Daily Living (NEADL) scale, EuroQol-5 Dimensions, ICEpop CAPability measure for Older people, General Self-Efficacy Scale, Falls Efficacy Scale - International (FES-I), Self-Efficacy for Exercise scale, Hospital Anxiety and Depression Scale (HADS) and service use measures. Outcome measures were assessed at baseline and at 3-month follow-up by blinded researchers.

RESULTS

Sixty-two participants were recruited (23% of those who were eligible), 61 were randomised (control, n = 32; intervention, n = 29) and 49 (79%) were followed up at 3 months. Compared with the cohort study, a younger, healthier subpopulation was recruited. There were minimal differences in most outcomes between the two groups, including the BADL index, with an adjusted mean difference of 0.5 (Cohen's d = 0.29). The intervention group showed a medium-sized improvement on the NEADL scale relative to the control group, with an adjusted mean difference between groups of 3.0 (Cohen's d = 0.63). There was a trend for greater improvement in FES-I and HADS in the intervention group, but with small effect sizes, with an adjusted mean difference of 4.2 (Cohen's d = 0.31) and 1.3 (Cohen's d = 0.20), respectively. The cost of delivering the intervention was £231 per patient. There was a possible small relative increase in quality-adjusted life-years in the intervention group. No serious adverse events relating to the intervention were reported.

CONCLUSIONS

Trial methods were feasible in terms of eligibility, recruitment and retention, although recruitment was challenging. The NEADL scale was more responsive than the BADL index, suggesting that the intervention could enable participants to regain better levels of independence compared with usual care. This should be tested in a definitive Phase III RCT. There were two main limitations of the study: the feasibility study lacked power to test for differences between the groups and a ceiling effect was observed in the primary measure.

TRIAL REGISTRATION

Current Controlled Trials ISRCTN22464643.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 21, No. 44. See the NIHR Journals Library for further project information.

The impact of surgeon volume and hospital volume on postoperative mortality and morbidity after hip fractures: A systematic review

INTRODUCTION

Recently, strategies aimed at optimizing provider factors have been proposed, including regionalization of surgeries to higher volume centers, and adoption of volume standards. With limited literature investigating the impact of hospital and surgeon volume on the outcome of hip fracture repairs, we undertook a systematic review to solidify the findings and attempt to arrive at a definitive conclusion with respect to both factors.

MATERIALS AND METHODS

We performed a systematic review examining the association between surgeon and hospital volume and hip fracture outcomes. To be included in the review, the study population had to include patients undergoing any hip fracture repair such as hemiarthroplasty (HA), internal fixation (ORIF) and total hip arthroplasty (THA). A total of five studies investigating surgeon volume and twelve studies investigating hospital volume were included in the study. With the exception of one study investigating both surgeon and hospital volume, volume thresholds were defined for all studies.

RESULTS

Studies were variable in defining surgeon and hospital volume thresholds. Low surgeon volume was associated with a longer LOS and a higher risk of mortality, but results were contrasting with respect to postoperative complications. High volume hospitals fared better than low volume with respect to length of stay, postoperative complications and time to surgery.

CONCLUSIONS

Increasing hospital volume was a more stronger predictor of postoperative outcomes as compared to surgeon volume. However, there are still few researches with respect to surgeon volume and further studies may yield a more definitive answer to this question.

Effect of Surgeon and Hospital Volume on Morbidity and Mortality After Hip Fracture

BACKGROUND

Prior studies have examined the relationship between surgeon and hospital volumes and outcome following hip fracture surgical procedures, but the results have been inconclusive. The purpose of this study was to assess the hip fracture volume-outcome relationship by analyzing data from a large, managed care registry.

METHODS

The Kaiser Permanente Hip Fracture Registry prospectively records information on surgically treated hip fractures within the managed health-care system. Using this registry, all surgically treated hip fractures in patients 60 years of age or older were identified. Surgeon and hospital volume were defined as the number of hip fracture surgical procedures performed in the preceding 12 months and were divided into tertiles (low, medium, and high). The primary outcome was mortality at 1 year postoperatively. Secondary outcomes were mortality at 30 and 90 days postoperatively as well as reoperation (lifetime), medical complications (90-day), and unplanned readmission (30-day). To determine the relationship between volume and these outcome measures, multivariate logistic and Cox proportional hazards regression were performed, controlling for potentially confounding variables.

RESULTS

Of 14,294 patients in the study sample, the majority were female (71%) and white (79%), and the mean age was 81 years. The overall mortality rate was 6% at 30 days, 11% at 90 days, and 21% at 1 year. We did not find an association between surgeon or hospital volume and mortality at 30 days, 90 days, or 1 year (p > 0.05). There was also no association between surgeon or hospital volume and reoperation, medical complications, or unplanned readmission (p > 0.05).

CONCLUSIONS

In this analysis of hip fractures treated in a large integrated health-care system, the observed rates of mortality, reoperation, medical complications, and unplanned readmission did not differ by surgeon or hospital volume. In contrast to other orthopaedic procedures, such as total joint arthroplasty, our data do not suggest that hip fractures need to be preferentially directed toward high-volume surgeons or hospitals for treatment.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

The life-saving effect of hospital proximity

We provide a new assessment of the effect of hospital proximity in an emergency situation-road-traffic accidents-exploiting the exogenous variation in the proximity to cities that are legally allowed to have a hospital on the basis of their population size. Our instrumental variable results show that a one-standard-deviation increase in the distance to the nearest hospital (5 km) raises the fatality rate by 13.84% at the sample average. This figure is equal to 0.92 additional deaths per 100 accidents. We show that both ordinary least squares and difference-in-differences estimates, common approaches in the literature, provide a downward-biased measure of the true effect of hospital proximity because they do not fully solve spatial sorting problems. Proximity is more important when the level of road safety is low, when emergency services are less responsive, and when the nearest hospital has relatively low quality standards.

Variation between Hospitals with Regard to Diagnostic Practice, Coding Accuracy, and Case-Mix. A Retrospective Validation Study of Administrative Data versus Medical Records for Estimating 30-Day Mortality after Hip Fracture

BACKGROUND

The purpose of this study was to assess the validity of patient administrative data (PAS) for calculating 30-day mortality after hip fracture as a quality indicator, by a retrospective study of medical records.

METHODS

We used PAS data from all Norwegian hospitals (2005-2009), merged with vital status from the National Registry, to calculate 30-day case-mix adjusted mortality for each hospital (n = 51). We used stratified sampling to establish a representative sample of both hospitals and cases. The hospitals were stratified according to high, low and medium mortality of which 4, 3, and 5 hospitals were sampled, respectively. Within hospitals, cases were sampled stratified according to year of admission, age, length of stay, and vital 30-day status (alive/dead). The final study sample included 1043 cases from 11 hospitals. Clinical information was abstracted from the medical records. Diagnostic and clinical information from the medical records and PAS were used to define definite and probable hip fracture. We used logistic regression analysis in order to estimate systematic between-hospital variation in unmeasured confounding. Finally, to study the consequences of unmeasured confounding for identifying mortality outlier hospitals, a sensitivity analysis was performed.

RESULTS

The estimated overall positive predictive value was 95.9% for definite and 99.7% for definite or probable hip fracture, with no statistically significant differences between hospitals. The standard deviation of the additional, systematic hospital bias in mortality estimates was 0.044 on the logistic scale. The effect of unmeasured confounding on outlier detection was small to moderate, noticeable only for large hospital volumes.

CONCLUSIONS

This study showed that PAS data are adequate for identifying cases of hip fracture, and the effect of unmeasured case mix variation was small. In conclusion, PAS data are adequate for calculating 30-day mortality after hip-fracture as a quality indicator in Norway.

Hospital case volume and outcomes for proximal femoral fractures in the USA: an observational study

OBJECTIVE

To explore whether older adults with isolated hip fractures benefit from treatment in high-volume hospitals.

DESIGN

Population-based observational study.

SETTING

All acute hospitals in California, USA.

PARTICIPANTS

All individuals aged ≥65 that underwent an operation for an isolated hip fracture in California between 2007 and 2011. Patients transferred between hospitals were excluded.

PRIMARY AND SECONDARY OUTCOMES

Quality indicators (time to surgery) and patient outcomes (length of stay, in-hospital mortality, unplanned 30-day readmission, and selected complications).

RESULTS

91,401 individuals satisfied the inclusion criteria. Time to operation and length of stay were significantly prolonged in low-volume hospitals, by 1.96 (95% CI 1.20 to 2.73) and 0.70 (0.38 to 1.03) days, respectively. However, there were no differences in clinical outcomes, including in-hospital mortality, 30-day re-admission, and rates of pneumonia, pressure ulcers, and venous thromboembolism.

CONCLUSIONS

These data suggest that there is no patient safety imperative to limit hip fracture care to high-volume hospitals.

A systematic review of the impact of center volume in dialysis

BACKGROUND

A significant relationship exists between the volume of surgical procedures that a given center performs and subsequent outcomes. It seems plausible that such a volume-outcome relationship is also present in dialysis.

METHODS

MEDLINE and EMBASE were searched in November 2014 for non-experimental studies evaluating the association between center volume and patient outcomes [mortality, morbidity, peritonitis, switch to hemodialysis (HD) or any other treatment], without language restrictions or other limits. Selection of relevant studies, data extraction and critical appraisal were performed by two independent reviewers. We did not perform meta-analysis due to clinical and methodological heterogeneity (e.g. different volume categories).

RESULTS

16 studies met out inclusion criteria. Most studies were performed in the US. The study quality ranged from fair to good. Only few items were judged to have a high risk of bias, while many items were judged to have an unclear risk of bias due to insufficient reporting. All 10 studies that analyzed peritoneal dialysis (PD) technique survival by modeling switch to HD or any other treatment as an outcome showed a statistical significant effect. The relative effect measures ranged from 0.25 to 0.94 (median 0.73) in favor of high volume centers. All nine studies indicated a lower mortality for PD in high volume centers, but only study was statistical significant.

CONCLUSIONS

This systematic review supports a volume-outcome relationship in peritoneal dialysis with respect to switch to HD or any other treatment. An effect on mortality is probably present in HD. Further research is needed to identify and understand the associations of center volume that are causally related to patient benefit.

European Regional Differences in All-Cause Mortality and Length of Stay for Patients with Hip Fracture

The objective of this study was to compare healthcare performance for the surgical treatment of hip fractures across and within Finland, Hungary, Italy, the Netherlands, Norway, Scotland, and Sweden. Differences in age-adjusted and sex-adjusted 30-day and one-year all-cause mortality rates following hip fracture, as well as the length of stay of the first hospital episode in acute care and during a follow up of 365 days, were investigated, and associations between selected country-level and regional-level factors with mortality and length of stay were assessed. Hungary showed the highest one-year mortality rate (mean 39.7%) and the lowest length of stay in one year (12.7 days), whereas Italy had the lowest one-year mortality rate (mean 19.1 %) and the highest length of stay (23.3 days). The observed variations were largely explained by country-specific effects rather than by regional-level factors. The results show that there should still be room for efficiency gains in the acute treatment of hip fracture, and clinicians, healthcare managers, and politicians should learn from best practices. This study demonstrates that an international comparison of acute hospital care is possible using pooled individual-level administrative data.

Minimum volume standards in German hospitals: do they get along with procedure centralization? A retrospective longitudinal data analysis

BACKGROUND

Compliance with minimum volume standards for specific procedures serves as a criterion for high-quality patient care. International experiences report a centralization of the respective procedures. In Germany, minimum volume standards for hospitals were introduced in 2004 for 5 procedures (complex esophageal and pancreatic interventions; liver, kidney and stem cell transplantations), in 2006 total knee replacement was added. This study explores whether any centralization is discernible for these procedures in Germany.

METHODS

A retrospective longitudinal analysis of secondary data serves to determine a possible centralization of procedures from the system perspective. Centralization means that over time, fewer hospitals perform the respective procedure, the case volume in high-volume hospitals increases together with their percentage of the annual total case volume, and the case volume in low-volume hospitals decreases together with their percentage of the annual total case volume. Using data from the mandatory hospital quality reports for the years 2006, 2008 and 2010 we performed Kruskal Wallis and chi-square tests to evaluate potential centralization effects.

RESULTS

No centralization was found for any of the six types of interventions over the period from 2006 to 2010. The annual case volume and the number of hospitals performing interventions rose at differing rates over the 5-year period depending on the type of intervention. Seven percent of esophagectomies and 14% of pancreatectomies are still performed in hospitals with less than 10 interventions per year.

CONCLUSIONS

For the purpose of further centralization of interventions it will be necessary to first analyze and then appropriately address the reasons for non-compliance from the hospital and patient perspective.

The volume-outcome relationship and minimum volume standards--empirical evidence for Germany

For decades, there is an ongoing discussion about the quality of hospital care leading i.a. to the introduction of minimum volume standards in various countries. In this paper, we analyze the volume-outcome relationship for patients with intact abdominal aortic aneurysm and hip fracture. We define hypothetical minimum volume standards in both conditions and assess consequences for access to hospital services in Germany. The results show clearly that patients treated in hospitals with a higher case volume have on average a significant lower probability of death in both conditions. Furthermore, we show that the hypothetical minimum volume standards do not compromise overall access measured with changes in travel times.

Factors influencing surgical delay after hip fracture in hospitals of Emilia Romagna Region, Italy: a multilevel analysis

Hip fracture is becoming a major public health concern, with associated mortality and morbidity particularly in the elderly. This study aims to investigate factors (i.e. patient factors and hospital variables) associated with increased risk for delaying surgery after hip fractures, and to assess whether and to what extent timing was associated with mortality risk. All patients aged 65 and over, resident in Emilia Romagna Region (Italy) and admitted to hospital for hip fracture (2009 - 2010) were selected. Data on surgical delay were adjusted using multilevel logistic regression model. A Cox proportional hazard model was fitted to a propensity score matched sample to assess mortality between delayed and early treated patients. Of the 10, 995 patients included (mean age: 83.3 years), 44.9% underwent surgery within 2 days. Significant risk factors for delayed surgery were: gender (OR: 1.16), comorbidity (OR: 1.29), anticoagulant (OR: 7.64) ,antiplatelet medication (OR: 2.43) , type of procedure (OR: 1.37) and day of admission (OR: Thu-Fri: 6.05; Sat-Sun: 1.17). Type of hospital and annual volume of hip fracture surgeries were not sufficient to explain hospital variability. A significant difference in mortality rate between early and delayed surgery emerged six months post surgery.

The trends in treatment of femoral neck fractures in the Medicare population from 1991 to 2008

BACKGROUND

We examined trends in the treatment of femoral neck fractures over the last two decades.

METHODS

We used Medicare Part A administrative data to identify patients hospitalized for closed femoral neck fracture from 1991 to 2008. We used codes from the International Classification of Diseases, Ninth Revision, to categorize treatment as nonoperative, internal fixation, hemiarthroplasty, and total hip arthroplasty. We examined differences in treatment according to hospital hip fracture volume, hospital location (rural or urban), and teaching status.

RESULTS

Our sample consisted of 1,119,423 patients with intracapsular hip fractures occurring from 1991 to 2008. We found a generally stable trend over time in the percentage of patients managed with nonoperative treatment, internal fixation, hemiarthroplasty, and total hip arthroplasty. We found little difference in surgical treatment across different groups of hospitals (high volume compared with low volume, urban compared with rural, and teaching compared with nonteaching). The percentage of acute care hospitals treating hip fractures remained fairly constant (74.8% in 1991 to 1993 and 69.0% in 2006 to 2008). The median number of hip fractures treated per hospital did not change (thirty-three in 1991 to 1993 and thirty-three in 2006 to 2008). There was no increase in the percentage of fractures treated in high-volume hospitals over time (57.7% in 1991 to 1993 and 57.1% in 2006 to 2008) and little reduction in the percentage of fractures treated in low-volume hospitals (5.8% in 1991 to 1993 and 5.5% in 2006 to 2008).

CONCLUSIONS

There has been little change in the trends of operative and nonoperative treatment for proximal femoral fractures over the last two decades, and there was little evidence of regionalization of hip fracture treatment to higher-volume hospitals.

Assessing the relationship between volume and outcome in hospital services: implications for service centralization

Proposals for centralizing services are often justified on the basis of studies linking the volume of activity to the outcomes achieved. However, the evidence of such studies is far from demonstrating a causal link between volume and outcome. This article assesses the main reasons why volume and outcome studies do not in themselves demonstrate a causal link, and therefore do not provide adequate support for proposals for centralizing hospital services. It then sets out a number of precepts to guide those responsible for proposing centralization of services.