Measuring Change in Key HRQL Outcomes Using MOS SF-36 vs VSAQ and BDI With Patients Undergoing CABG Surgery

Abstract

Health-related quality of life (HRQL) measures taken before and after coronary artery bypass grafting (CABG) aid in determining meaningful patient-perceived outcomes associated with alternative clinical interventions. This study compared performance of the Medical Outcomes Study Short Form-36 (MOS SF-36) subscales for Physical Functioning (PF), Role Physical (RP), Mental Health (MH), and Role Emotional (RE) against two other questionnaires, i.e. the Veteran's Specific Activity Questionnaire (VSAQ: self-efficacy for vigorous physical activity) and the Beck Depression Inventory (BDI-II: mental-emotional functioning). Seventy-one patients (59-M; 12-F; age, Mean + SD = 63 ± 8.6 years) were administered these three questionnaires just before and 3 months following CABG surgery. Score distributions were evaluated for the pre- and post-surgery measurements, as were change scores after CABG. All measures except the MOS SF-36 subscales for RP and RE showed statistically significant change after CABG (p<0.01). Only the subscales of RP and RE demonstrated substantial ceiling (21.0% and 56.3%) and floor effects (49.3% and 16.9%). Evaluation of individual change scores after CABG indicated that 59% and 62% of the patients, respectively, had clinically meaningful increases in the two measures of physical capability, i.e. PF and VSAQ. In contrast, 60% and 72% of patients, respectively, showed no clinically meaningful changes in the two measures of emotional functioning, i.e. RE and BDI-II scores. Chi-square analyses revealed that use of scales with similar definitional constructs resulted in significantly different surgical outcomes for the following: PF vs VSAQ (p<0.001), RP vs VSAQ (p<0.02); and MH vs BDI-II (p<0.0001). These findings illustrate the limitations in performance of the MOS SF-36 for assessing changes of importance in HRQL after CABG. The VSAQ and BDI-II, two simple measures of physical and emotional functioning that are fundamentally similar to those contained in the MOS SF-36, appear to be sensitive markers for detecting changes in these important outcomes after CABG surgery.