A comparison of 3 generic health status questionnaires among stroke patients

Several generic multidimensional health status questionnaires are available, but it is not clear whether or not these measures are interchangeable in terms of content. Consequently, we investigated the content validity of the Sickness Impact Profile 68 (SIP68), Medical Outcome Study Short Form 36 (SF-36), and the Darmouth COOP Functional Health Assessment Charts/World Organization of National Colleges, Academies and Academic Associations of General Practitioners/Family Physicians (COOP/WONCA) charts. A total of 198 stroke patients referred to inpatient rehabilitation were interviewed 1 year poststroke. Subscales of the generic questionnaires were compared with one another and also with 3 domain-specific scales: the Barthel Index (BI) for physical functioning, the Center of Epidemiology Studies Depression (CES-D) scale for mental functioning, and the Frenchay Activities Index (FAI) for social functioning. Nonparametric Spearman correlations of at least 0.6 were accepted as evidence of content validity. Half of the physical subscales correlated with each other by at least 0.6. None of the 3 correlations in the mental domain and only 1 of 21 correlations in the social domain met the 0.6 threshold. Physical-oriented subscales correlated with BI almost as expected. In the mental domain, only the correlation of the CES-D with the SF-36 mental health scale was above 0.6, and in the social domain, only the correlation of the FAI with the SIP68 mobility range was above 0.6. The findings of this study suggest that generic health questionnaires are not mutually interchangeable. Physical and social health status of stroke patients is adequately covered by the SIP68. However, the SF-36 is more suitable for measuring the mental consequences of stroke.