Total Joint Replacement Outcomes for Men and Women Treated at VA Hospitals: Results from a National Study

Weaver FM, Hynes DM, Ippolito D, Cull W, Thakkar B, Gibbs J. Total Joint Replacement Outcomes for Men and Women Treated at VA Hospitals: Results from a National Study. Paper presented at: American Public Health Association Annual Meeting and Exposition; 1999 Nov 1; Chicago, IL.

Research Objective: To explore and examine relationships between patient sociodemographic, preoperative risk, structure and process characteristics and clinical outcomes of men and women undergoing total knee replacements (TKR) and total hip replacements (THR) at VAMCs.Study Design: Using information collected from the Department of Veterans Affairs (VA) National Surgical Quality Improvement Program (NSQIP), we identified all TKR (partial, total, revision, and removal) and THR (partial, total, conversion, and revision) procedures performed at VA facilities between October, 1992 and September, 1997. The NSQIP contains data on 62 preoperative risk and demographic characteristics, four process, and 23 outcome variables. We supplemented the NSQIP with data from the VA's Patient Treatment File for readmission data, pathology reports from sites, and facility characteristic data. Data from these sources were merged on patient identifiers and procedure date. Any hospitalizations that occurred within one year of the procedure were captured. Outcomes of interest include: postoperative length of stay, morbidity within 30 days (i.e., one or more of 21 complications monitored by the NSQIP), and any readmissions that occurred as a result of a complication of the procedure within one year post surgery. We also identified total joint replacement specific-complications. An initial list was based on one developed for a similar Health Care Financing Administration study by Riley and colleagues (1993). We updated the list with consultation from two orthopedic surgeons who identified additional relevant diagnostic codes and assigned a time period within which the diagnosis would be considered a complication. Principal Findings: Over a six year period, VA performed 13,889 total knee replacements ( 3.2% female; 96.8% male) and 10,938 total hip replacements (2.9% female; 97.1% male). Patients were predominately white (83% TKR; 80% THR). The average age was 66.1 years for TKR and 64.8 years for THR, and 67% TKR and 52% THR were married. Preoperatively, 20% TKR and 31% THR were smokers, 48% TKR and 39% THR had a history of hypertension requiring medications, and 8% TKR and 13% THR were frequent alcohol users. The mean length of stay for TKR was 11.2 days (sd = 9.2) for women and 9.9 days (sd = 8.6) for men; whereas the mean length of stay for THR was 12.8 days (sd = 14.8) for women and 12.1 days (sd = 12.8) for men. Within 30 days of a TKR, 10% of women and 8% of men experienced one or more of the 21 complications defined by the NSQIP. For THR, 13% of women and 14% of men experienced one or more complications. Mortality rates were 0.5% for TKR and 2% for THR. Logistic regression modeling of 30-day morbidity for TKR identified 9 significant predictors with a c-index = 0.628. Predictors included gender, race, age, hospital size, pulmonary disease, functional status, and total operation time. Modeling for 30-morbidity for THR identified 13 significant predictors including age, functional status, comorbid conditions and pre-operative health status (e.g., pulmonary disease, congestive heart failure, weight loss, cancer), hospital size based on patient volume, and whether or not the case was an emergency procedure (c-index = 0.697). Additional analyses will examine the gender effect in more detail including identifying individuals with osteoarthritis and rheumatoid arthritis. Outcome modeling focusing on readmission outcomes is in process. Conclusions: Research on TJR outcomes have tended to focus on single outcomes and limited examination of preoperative characteristics. This work examining multiple preoperative characteristics and outcomes indicates that age, comorbid conditions and poor health status are significant predictors of 30-day morbidity for TJR. For TKR, gender and race were also significant predictors of 30-day morbidity. For THR, emergency procedures may be indicative of hip fracture cases. Implications for Policy, Delivery or Practice: This research will provide insight about the relationships between patientsociodemographic, preoperative risk, structure and process characteristics and clinical outcomes of men and women undergoing total hip replacements and total knee replacements at VA hospitals across the United States. Information learned from this study may be useful in quality improvement efforts in VA and may have implications for TJR surgery in non-VA settings. Primary Funding Source: Department of Veterans Affairs, Health Services Research and Development Service