Validity, Reliability, and Responsiveness of the Anterior Cruciate Ligament Quality of Life Measure: A Continuation of Its Overall Validation.

OBJECTIVE

The purpose is to provide more validity, reliability, and responsiveness testing of the anterior cruciate ligament-quality of life instrument (ACL-QOL), particularly in light of consensus-based standards for the selection of health status measurement instruments (COSMIN) guidelines.

DESIGN

Prospective case series.

SETTING

An orthopedic surgical practice for consultation.

PATIENTS

A convenience sample of 579 ACL-deficient patients.

INTERVENTION

Anterior cruciate ligament reconstructive surgery.

MAIN OUTCOME MEASURES

Patients completed the ACL-QOL at initial visit and underwent reconstructive surgery. Patients were followed at 6, 12, and 24 months using the ACL-QOL to determine its validity and responsiveness. Cronbach's alpha was used to determine the unidimensionality of the ACL-QOL. A subset of patients took the ACL-QOL twice in a test-retest reliability analysis (intraclass correlation coefficient or ICC 2,k). Another subset of 24-month postsurgical patients measured the success of their surgery using a 7-point global rating scale of improvement as an anchor-based method of responsiveness.

RESULTS

Cronbach's alpha coefficients = 0.93, 0.95, 0.96, and 0.98 at 6, 12, and 24 months, respectively. Intraclass correlation coefficient = 0.60, SEM = 6.16, and confidence interval of 12.1 (CI 95%). Responsiveness was measured by comparing the 4 serial time periods. Patients improved significantly at each time period (P < 0.05, ETA squared 0.61). A 24-month ACL-QOL was significantly correlated (P > 0.05) to being "significantly better" or "somewhat better."

CONCLUSIONS

The results of this study added more validity, reliability, and responsiveness for the ACL-QOL. The ACL-QOL has completed 8 of 9 COSMIN criteria.