Comparative effectiveness of peripheral vascular intervention versus surgical bypass for critical limb ischemia in the Vascular Study Group of Greater New York

Journal Journal of Vascular Surgery
Authors Meltzer AJ, Sedrakyan A, Isaacs A, Connolly PH, Schneider DB
Year Published 2016
Link to publication

Abstract

OBJECTIVE:

In this study, the effectiveness of peripheral vascular intervention (PVI) was compared with surgical bypass grafting (BPG) for critical limb ischemia (CLI) in the Vascular Study Group of Greater New York (VSGGNY).

METHODS:

Patients undergoing BPG or PVI for CLI at VSGGNY centers (2011-2013) were included. The Society for Vascular Surgery objective performance goals for CLI were used to directly compare the safety and effectiveness of PVI and BPG. Propensity score matching was used for risk-adjusted comparisons of PVI with BPG.

RESULTS:

A total of 414 patients (268 PVI, 146 BPG) were treated for tissue loss (69%) or rest pain (31%). Patients undergoing PVI were more likely to have tissue loss (74.6% vs 57.5%; P < .001) and comorbidities such as diabetes (69.3% vs 57.5%; P = .02), heart failure (22% vs 13.7%; P = .04), and severe renal disease (13.1% vs 4.1%; P = .004). No significant differences were found between the groups across a panel of safety objective performance goals. In unadjusted analyses at 1 year, BPG was associated with higher rates of freedom from reintervention, amputation, or restenosis (90.4% vs 81.7%; P = .02) and freedom from reintervention or amputation (92.5% vs 85.8%, P = .045). After propensity score matching, PVI was associated with improved freedom from major adverse limb events and postoperative death at 1 year (95.6% vs 88.5%; P < .05).

CONCLUSIONS:

By unadjusted comparison, early reintervention and restenosis are more prevalent with PVI. However, risk-adjusted comparison underscores the safety and effectiveness of PVI in the treatment of CLI.

Regulator loss functions and hierarchical modeling for safety decision making

Journal Medical Decision Making
Authors Hatfield LA, Baugh CM, Azzone V, Normand S-LT
Year Published 2017
Link to publication

Abstract

Background

Regulators must act to protect the public when evidence indicates safety problems with medical devices. This requires complex trade-offs among risks and benefits, which conventional safety surveillance methods do not incorporate.

Objective

To combine explicit regulator loss functions with statistical evidence on medical device safety signals to improve decision-making.

Methods

In the Hospital Cost and Utilization Project National Inpatient Sample, we select pediatric inpatient admissions and identify adverse medical device events (AMDEs). We fit hierarchical Bayesian models to the annual hospital-level AMDE rates, accounting for patient and hospital characteristics. These models produce expected AMDE rates (a safety target), against which we compare the observed rates in a test year to compute a safety signal. We specify a set of loss functions that quantify the costs and benefits of each action as a function of the safety signal. We integrate the loss functions over the posterior distribution of the safety signal to obtain the posterior (Bayes) risk; the preferred action has the smallest Bayes risk. Using simulation and an analysis of AMDE data, we compare our minimum-risk decisions to a conventional Z score approach for classifying safety signals.

Results

The two rules produced different actions for nearly half of hospitals (45%). In the simulation, decisions that minimize Bayes risk outperform Z score-based decisions, even when the loss functions or hierarchical models are misspecified.

Limitations

Our method is sensitive to the choice of loss functions; eliciting quantitative inputs to the loss functions from regulators is challenging.

Conclusions

A decision theoretic approach to acting on safety signals is potentially promising, but requires careful specification of loss functions in consultation with subject matter experts.

Nursing Home Use After Implantable Cardioverter-Defibrillator Implantation in Older Adults: Results from the National Cardiovascular Data Registry

Journal Journal of the American Geriatrics Society
Authors Kramer DB, Reynolds MR, Normand SL, Parzynski CS, Spertus JA, Mor V, Mitchell SL.
Year Published 2017
Link to publication

Abstract

To evaluate the incidence and characteristics of nursing home (NH) use after implantable cardioverter-defibrillator (ICD) implantation.

DESIGN:

Cohort study.

SETTING:

Medicare beneficiaries in the National Cardiovascular Data Registry-ICD Registry.

PARTICIPANTS:

Individuals aged 65 and older receiving ICDs between January 1, 2006, and March 31, 2010 (N = 192,483).

MEASUREMENTS:

Proportion of ICD recipients discharged to NHs directly after device placement, cumulative incidence of long-term NH admission, and factors associated with immediate discharge to a NH and time to long-term NH admission.

RESULTS:

Over 4 years, 40.6% of the cohort died, and 35,939 (18.7%) experienced at least one NH admission, including 4.0% directly discharged to a NH after ICD implantation and 2.8% admitted to long-term NH care during follow-up. The cumulative incidence of long-term NH admission, accounting for the competing risk of death, was 1.7% at 1 year, 3.8% at 3 years, and 4.6% at 4 years; 20.1% of individuals admitted to a NH died there. Factors most strongly associated with direct NH discharge and time to long-term NH care were older age (adjusted odds ratio (AOR) = 2.09, 95% confidence interval (CI) = 2.01-2.17 per 10-year increment; adjusted hazard ratio (AHR) = 1.88, 95% CI = 1.80-1.97, respectively), dementia (AOR = 2.60, 95% CI = 2.25-3.01; AHR = 2.50, 95% CI = 2.14-2.93, respectively), and Medicare Part A claim for NH stay in prior 6 months (AOR = 3.96, 95% CI = 3.70-4.25; AHR = 2.88, 95% CI = 2.65-3.14, respectively).

CONCLUSION:

Nearly one in five individuals are admitted to NHs over a median of 1.6 years of follow-up after ICD implantation. Understanding these outcomes may help inform the clinical care of these individuals.

Reoperation after breast-conserving surgery for cancer in Australia: statewide cohort study of linked hospital data

Journal BMJ Open
Authors van Leeuwen MT, Falster MO, Vajdic CM, Crowe PJ, Lujic S, Klaes E, Jorm L, Sedrakyan A
Year Published 2018
Link to publication

Abstract

OBJECTIVES:

To investigate between-hospital variation in the probability of reoperation within 90 days of initial breast-conserving surgery (BCS), and the contribution of health system-level and other factors.

DESIGN:

Population-based, retrospective cohort study.

SETTING:

New South Wales (NSW), Australia.

PARTICIPANTS:

Linked administrative hospitalisation data were used to define a cohort of adult women undergoing initial BCS for breast cancer in NSW between 1 July 2002 and 31 December 2013.

PRIMARY OUTCOME MEASURES:

Multilevel, cross-classified models with patients clustered within hospitals and residential areas were used to examine factors associated with any reoperation, and either re-excision or mastectomy, within 90 days.

RESULTS:

Of 34 458 women undergoing BCS, 29.1% underwent reoperation within 90 days, half of which were mastectomies. Overall, the probability of reoperation decreased slightly over time. However, there were divergent patterns by reoperation type; the probability of re-excision increased alongside a concomitant decrease in the probability of mastectomy. Significant between-hospital variation was observed. Non-metropolitan location and surgery at low-volume hospitals were associated with a higher overall probability of reoperation, and of mastectomy specifically, after accounting for patient-level factors, calendar year and area-level socioeconomic status. The magnitude of association with geographical location and surgical volume decreased over time.

CONCLUSIONS:

Reoperation rates within 90 days of BCS varied significantly between hospitals. For women undergoing mastectomy after BCS, this represents a dramatic change in clinical course. Multilevel modelling suggests unwarranted clinical variation may be an issue, likely due to disparities in access to multidisciplinary breast cancer care and preoperative diagnostic procedures. However, the observed reduction in disparities over time is encouraging and indicates that guidelines and policy initiatives have the potential to improve regional breast cancer care.

Comparing Long-term Mortality After Carotid Endarterectomy vs Carotid Stenting Using a Novel Instrumental Variable Method for Risk Adjustment in Observational Time-to-Event Data

Journal JAMA Network Open
Authors Jesse A. Columbo; Pablo Martinez-Camblor; Todd A. MacKenzie; Douglas O. Staiger; Ravinder Kang; Philip P. Goodney; A. James O’Malley
Year Published 2018
Link to publication

Abstract

IMPORTANCE:

Choosing between competing treatment options is difficult for patients and clinicians when results from randomized and observational studies are discordant. Observational real-world studies yield more generalizable evidence for decision making than randomized clinical trials, but unmeasured confounding, especially in time-to-event analyses, can limit validity.

OBJECTIVES:

To compare long-term survival after carotid endarterectomy (CEA) and carotid artery stenting (CAS) in real-world practice using a novel instrumental variable method designed for time-to-event outcomes, and to compare the results with traditional risk-adjustment models used in observational research for survival analyses.

DESIGN, SETTING, AND PARTICIPANTS:

A multicenter cohort study was performed. The Vascular Quality Initiative, an observational quality improvement registry, was used to compare long-term mortality after CEA vs CAS. The study included 86 017 patients who underwent CEA (n = 73 312) or CAS (n = 12 705) between January 1, 2003, and December 31, 2016. Patients were followed up for long-term mortality assessment by linking the registry data to Medicare claims. Medicare claims data were available through September 31, 2015.

EXPOSURE:

Procedure type (CEA vs CAS).

MAIN OUTCOMES AND MEASURES:

The hazard ratios (HRs) of all-cause mortality using unadjusted, adjusted, propensity-matched, and instrumental variable methods were examined. The instrumental variable was the proportion of CEA among the total carotid procedures (endarterectomy and stenting) performed at each hospital in the 12 months before each patient’s index operation and therefore varies over the study period.

RESULTS:

Participants who underwent CEA had a mean (SD) age of 70.3 (9.4) years compared with 69.1 (10.4) years for CAS, and most were men (44 191 [60.4%] for CEA and 8117 [63.9%] for CAS). The observed 5-year mortality was 12.8% (95% CI, 12.5%-13.2%) for CEA and 17.0% (95% CI, 16.0%-18.1%) for CAS. The unadjusted HR of mortality for CEA vs CAS was 0.67 (95% CI, 0.64-0.71), and Cox-adjusted and propensity-matched HRs were similar (0.69; 95% CI, 0.65-0.74 and 0.71; 95% CI, 0.65-0.77, respectively). These findings are comparable with published observational studies of CEA vs CAS. However, the association between CEA and mortality was more modest when estimated by instrumental variable analysis (HR, 0.83; 95% CI, 0.70-0.98), a finding similar to data reported in randomized clinical trials.

CONCLUSIONS AND RELEVANCE:

The study found a survival advantage associated with CEA over CAS in unadjusted and Cox-adjusted analyses. However, this finding was more modest when using an instrumental variable method designed for time-to-event outcomes for risk adjustment. The instrumental variable-based results were more similar to findings from randomized clinical trials, suggesting this method may provide less biased estimates of time-dependent outcomes in observational analyses.