Predictors of quality of life 6 months and 1 year after acute myocardial infarction.

BACKGROUND: Quality of life (QOL) is an increasingly important outcome measure after hospital admission for acute myocardial infarction (AMI). However, the ability to adjust these outcomes for differences between compared groups of patients is limited because the predictors of QOL after AMI are unknown.
METHODS: To identify any clinical, demographic, and psychosocial characteristics of patients at admission that were independent predictors of QOL 6 months and 1 year after AMI, we measured physical and mental QOL (Short Form-36 Physical and Mental Component summary scores) and overall QOL (EuroQol health perception scale) in a prospective cohort of 587 patients admitted at 10 hospitals in Quebec. A set of plausible multivariate linear regression models was created for each outcome measure with use of the Bayesian Information Criterion.
RESULTS: Mean physical, mental, and overall QOL scores corresponding to the time immediately before admission (baseline) were 45 (95% confidence interval [CI] 44-46), 47 (95% CI 46-48), and 70 (95% CI 68-72), respectively. By 1 year, mean physical, mental, and overall QOL scores were close to baseline (45 [95% CI 44-46], 48 [95% CI 47-49], and 73 [95% CI 71-74], respectively). The predictors of physical, mental, and overall QOL were similar at 6 months and 1 year. Important predictors of physical QOL were the corresponding score at baseline, age, and previous bypass surgery (beta coefficients at 1 year: 5 [per 10-point difference in baseline score], -1 [per 10-year age difference], 5.3; 95% CIs 4 to 5, -2 to -1, -9.2 to -1.3, respectively). Predictors of mental QOL were the corresponding score at baseline and depression (beta coefficients at 1 year: 3 [per 10-point difference in baseline score], -3 [per 10-point difference in depression score]; 95% CIs 2 to 4, -5 to -2, respectively). Predictors of overall QOL included the corresponding score at baseline and age (beta at 1 year: 2 [per 10-point score difference], -3 [per 10-year age difference]; 95% CIs 1 to 3, -4 to -1, respectively). Depression was also a predictor of impaired physical and overall QOL at 6 months (beta at 6 months: -1.6 [per 10-point score difference], -5.4 [per 10-point score difference]; 95% CIs -2.9 to -0.4, -7.7 to -3.2, respectively). No variables related to treatments received in-hospital were found in the most clinically relevant models.
CONCLUSIONS: These results suggest that age and psychosocial characteristics at baseline are the most important predictors of QOL after AMI. Other clinical characteristics and treatments received in-hospital do not appear to strongly affect patients' long-term perceptions of QOL.