Is there a positive volume-outcome relationship in peripheral vascular surgery? Results of a systematic review

Exploring relationships between in-hospital mortality and hospital case volume using random forest: results of a cohort study based on a nationwide sample of German hospitals, 2016-2018

Background

Relationships between in-hospital mortality and case volume were investigated for various patient groups in many empirical studies with mixed results. Typically, those studies relied on (semi-)parametric statistical models like logistic regression. Those models impose strong assumptions on the functional form of the relationship between outcome and case volume. The aim of this study was to determine associations between in-hospital mortality and hospital case volume using random forest as a flexible, nonparametric machine learning method.

Methods

We analyzed a sample of 753,895 hospital cases with stroke, myocardial infarction, ventilation > 24 h, COPD, pneumonia, and colorectal cancer undergoing colorectal resection treated in 233 German hospitals over the period 2016–2018. We derived partial dependence functions from random forest estimates capturing the relationship between the patient-specific probability of in-hospital death and hospital case volume for each of the six considered patient groups.

Results

Across all patient groups, the smallest hospital volumes were consistently related to the highest predicted probabilities of in-hospital death. We found strong relationships between in-hospital mortality and hospital case volume for hospitals treating a (very) small number of cases. Slightly higher case volumes were associated with substantially lower mortality. The estimated relationships between in-hospital mortality and case volume were nonlinear and nonmonotonic.

Conclusion

Our analysis revealed strong relationships between in-hospital mortality and hospital case volume in hospitals treating a small number of cases. The nonlinearity and nonmonotonicity of the estimated relationships indicate that studies applying conventional statistical approaches like logistic regression should consider these relationships adequately.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12913-021-07414-z.

Differences of in-hospital outcomes within patients undergoing percutaneous coronary intervention at institutions with high versus low procedural volume: a report from the Japanese multicentre percutaneous coronary intervention registry

Objective

We aimed to determine the relationship between the prevalence of in-hospital complications and annual institutional patient volume in a population of patients undergoing percutaneous coronary intervention (PCI).

Methods

Clinical data of patients receiving PCI between January 2010 and June 2015 were collected from 14 academic institutions in the Tokyo area and subsequently used for analysis. We employed multivariate hierarchical logistic regression models to determine the effect of institutional volume on several in-hospital outcomes, including in-hospital mortality and procedure-related complications.

Results

A total of 14 437 PCI cases were included and categorised as receiving intervention from either lower-volume (<200 procedures/year, n=6 hospitals) or higher-volume (≥200 procedures/year, n=8 hospitals) institutions. Clinical characteristics differed significantly between the two patient groups. Specifically, patients treated in higher-volume hospitals presented with increased comorbidities and complex coronary lesions. Unadjusted mortality and complication rate in lower-volume and higher-volume hospitals were 1.3% and 1.2% (p=0.0614) and 6.2% and 8.1% (p=0.001), respectively. However, multivariate hierarchical logistic regression models adjusting for differences in the patient characteristics demonstrated that institutional volume was not associated with adverse clinical outcomes.

Conclusions

In conclusion, we observed no significant association between annual institutional volume and in-hospital outcomes within the contemporary PCI multicentre registry.

Trial registration number

UMIN R000005598.

Relative impact of hospital and surgeon procedure volumes on primary total hip arthroplasty revision: a nationwide cohort study in France

BACKGROUND

Both surgeon and hospital procedure volumes have been found to be associated with total hip arthroplasty (THA) outcomes. However, little research has been conducted on the relative influence. We studied the association between THA survivorship and both hospital and surgeon procedure volumes, considering their relative impact.

METHODS

A population-based cohort included all patients aged ≥40 years having received a unilateral primary THA from 2010 to 2011, from the French National Health Insurance Database. Patients were followed up until the end of 2014. The outcome was THA revision. Exposures of interest were procedure volumes, divided into tertiles: <1.5, 1.5-4, >4 and <7, 7-15, >15 procedures per month defined as low, medium, and high volumes for surgeon and hospital, respectively.

RESULTS

The cohort had 62,906 patients, with mean age 69 years and women 57%. Mean surgeon and hospital volumes were 8 and 23 procedures per month, respectively, and 5%, 72%, 22% and 7%, 28%, 65% of THAs were implanted by a low-, medium-, and high-volume surgeon or in a low-, medium-, and high-volume hospital, respectively. Median follow-up was 45 months (range, 0-57 months). In multivariate analysis, adjusted for both surgeon and hospital volumes, for patient and THA characteristics, a lower surgeon volume was associated with poorer THA survivorship (adjusted hazard ratio [aHR] = 1.19; 95% confidence interval [CI], 1.07-1.34 and aHR = 1.70; 95% CI, 1.40-2.05, for medium- and low-volume surgeon, respectively, compared with that of high volume), whereas hospital volume was not.

CONCLUSIONS

This study brings evidence to support the notion that THAs performed by high-volume surgeons in French private hospitals have higher survivorship in the first 4 years.

Relationship between surgeon volume and outcomes: a systematic review of systematic reviews

BACKGROUND

The surgeon volume-outcome relationship has been discussed for many years and its existence or nonexistence is of importance for various reasons. A lot of empirical work has been published on it. We aimed to summarize systematic reviews in order to present current evidence.

METHODS

Medline, Embase, Cochrane database of systematic reviews (CDSR), and health technology assessment websites were searched up to October 2015 for systematic reviews on the surgeon volume-outcome relationship. Reviews were critically appraised, and results were extracted and synthesized by type of surgical procedure/condition.

RESULTS

Thirty-two reviews reporting on 15 surgical procedures/conditions were included. Methodological quality of included systematic reviews assessed with the assessment of multiple systematic reviews (AMSTAR) was generally moderate to high albeit included literature partly neglected considering methodological issues specific to volume-outcome relationship. Most reviews tend to support the presence of a surgeon volume-outcome relationship. This is most clear-cut in colorectal cancer, bariatric surgery, and breast cancer where reviews of high quality show large effects.

CONCLUSIONS

When taking into account its limitations, this overview can serve as an informational basis for decision makers. Our results seem to support a positive volume-outcome relationship for most procedures/conditions. However, forthcoming reviews should pay more attention to methodology specific to volume-outcome relationship. Due to the lack of information, any numerical recommendations for minimum volume thresholds are not possible. Further research is needed for this issue.

Re-examining the significance of surgical volume to breast cancer survival and recurrence versus process quality of care in Taiwan

OBJECTIVE

This study explored the association of surgical volume versus process quality with breast cancer survival and recurrence.

DATA SOURCES/STUDY SETTING

Population-based cancer registration data and National Health Insurance claim data.

STUDY DESIGN

This population-based study linked Taiwan's Cancer Database with Taiwan's National Health Insurance Database to collect data on all patients diagnosed with breast cancer in 2003-2004 who received surgical treatment.

PRINCIPAL FINDINGS

This study included 6,396 female breast cancer patients, reported by 26 hospitals. After controlling for patient and provider characteristics, Cox's regression models did not reveal any association between a physician's surgical volume and breast cancer recurrence or survival, although hospital volume was marginally associated with positive 5-year recurrence (HR: 1.001, 95%CI: 1.000, 1.001). After controlling for hospital or physician volume of surgery, we found a significant association between quality of care and both 5-year survival and recurrence. Random effects were also identified between patients and providers based on 5-year survival and 5-year recurrence.

CONCLUSIONS

Process quality of care was significantly more related to survival or recurrence than to surgical volume. The random effects found within hospital-patient clustered data indicated that the effect of the clustered feature of this data should be considered when performing volume-outcome related studies.

Shaping the future of surgery: the role of private regulation in determining quality standards

OBJECTIVE

To educate surgeons about the growth of the private regulatory movement and its potential implications for the practice of surgery.

METHODS

An in-depth analysis and literature review of one of the largest private regulatory groups, the Leapfrog Group, provides a model for understanding the impact of these groups on the practice of surgery. A detailed discussion of the history, mission, structure, and quality initiatives of Leapfrog is included.

RESULTS

Private regulatory groups are using quality standards as a method for controlling the rising cost of health care. Traditionally, little financial support, manpower, or incentives have existed for individual surgeons and hospitals to report and maintain their own outcomes data. However, as surgical outcomes have increasingly become the target of quality improvement initiatives, the need to measure performance is gaining importance. Surgical quality has been both a direct target of private regulation, as illustrated by the evidence-based hospital referral guidelines of Leapfrog, and an indirect target with initiatives like computerized physician order entry and ICU staffing guidelines.

CONCLUSIONS

Private regulation is rapidly reshaping the way we practice and teach surgery. It is almost a certainty that their power, popularity, financial support, and missions will all continue to expand. As surgeons, we must decide soon if we wish to be an active participant in shaping the movement or, rather, if we are going to let it shape us by remaining largely uninvolved.