Caliber of quality-of-life assessments in congenital heart disease - A plea for more conceptual and methodological rigor

Background: Interest in quality-of-life issues in children, adolescents, and adults with congenital heart disease has increased significantly during the past decades. In general, quality-of-life research is stimulated by an overall interest in outcomes. More specifically, quality-of-life studies add to mortality and morbidity data by taking reported physical, psychological, and social problems into consideration. However, quality of life can be an ambiguous concept that is hindered by methodological weaknesses, a situation that can prevent the drawing of firm conclusions. Objective: To appraise the conceptual and methodological rigor of published quality-of-life assessments in patients with congenital heart disease. Design: A review of 70 articles published in the medical literature, using the 10 criteria previously developed by Gill and Feinstein. For each criterion, the number of articles complying with that criterion was counted, and the percentage was calculated. To indicate how well individual articles performed on the respective criteria, a summary score was calculated by summing the number of criteria an article fulfilled and dividing this sum by the number of criteria for which the article was eligible to be evaluated; the resulting value was then multiplied by 100. Main Outcome Measure: Summary scores ranging from 0, for articles complying with none of the criteria, to 100, for articles complying with all of the criteria. Results: We found that quality-of-life assessments in patients with congenital heart disease showed major conceptual and methodological drawbacks (median summary score, 0). Moreover, we found that the term quality of life was often used inappropriately, an observation supported by several articles in which the authors drew conclusions about patients' quality of life, even though quality of life was not specifically measured. Conclusions: A poor conceptual and methodological basis for quality of life implies that many results from quality-of-life studies performed in patients with congenital heart disease contribute little to the scientific knowledge base of quality of life in this patient population. Future quality-of-life studies need to invest in a rigorous conceptualization, an adequate operational definition, and a sound measurement of quality of life.