The Effect of Comorbidities Upon Health-Related Quality-of-Life

¹ Center for Value-Based Medicine, United States
² Center for Value-Based Medicine, Wills Eye Institute, United States

^* To whom correspondence should be addressed. E-mail: gary0514{at}aol.com.

Accepted 5 March 2008

	Abstract

Aim: The purpose of the study was to assess whether, and to what degree, comorbidities affect patient quality-of-life.

Methods: A cross-sectional, quality-of-life study of 170 consecutive vitreoretinal patients compared the utility associated with a participant's primary (most incapacitating) disease and the utility associated with a grouping of all of the participants' diseases. The ocular diseases present included diabetic retinopathy (44%), macular degeneration (30%), lattice degeneration/retinal tear (14%), retinal vascular obstruction (5%), uveitis, macular edema, macular pucker (5%) and others (2%). Participants underwent interviewer-administered, time tradeoff utility questions for each disease, then for a compilation of all diseases. Their primary disease was defined by the lowest utility reported for a single disease, while other health conditions were considered comorbidities. A two-tailed, paired t-test was used to compare the means of the primary disease utilities and compilation utilities. .The study was powered to have a 90% chance of detecting an 8% difference in mean utility between the two utility groups

Results: The mean lowest utility for the most disabling single health condition (primary disease) was 0.82 (Standard Deviation = 0.22; 95% Confidence Interval = 0.79 – 0.85. The mean utility for the grouping together of all diseases was 0.80 (SD± 0.24, 95% CI 0.76-0.84). No significant difference was found between the mean utilities of the two groups (p = 0.56).

Conclusions: The overall health-related quality-of-life of a patient in an ophthalmic population with serious diseases appears to be primarily determined by the single disease that most adversely affects the individual's quality-of-life. This conclusion has significant implications in clinical care and when considering the use of comorbidities in cost-utility analyses.