Margaret L. Rothman

The validity of proxy-generated scores as measures of patient health status.

This study examines the validity of proxy assessments as substitutes for patient assessments of patient physical and psychosocial health status. Data were obtained from 275 patient-proxy pairs who were enrolled in a national study of Adult Day Health Care. Patients and proxies (informal caregivers such as spouses) were asked to complete the Sickness Impact Profile (SIP) based on the patients health status. Findings showed that patient-generated and proxy-generated physical scores were highly correlated, although proxies rated patients as slightly more impaired than the patients rated themselves. The correlation between psychosocial scores was not high enough to consider proxy responses as valid substitutes for patient responses. We explored these differences in response by comparing regression equations predicting patient-generated and proxy-generated physical and psychosocial SIP dimension scores. Variance in the patient-generated psychosocial score was explained by physical function, psychological distress, cognitive status and patient age. Proxygenerated psychosocial scores were primarily explained by the caregivers psychological distress and perceived burden. These findings point out the importance of considering the source of patient health status estimates when interpreting the results of research studies.

The Sickness Impact Profile as a measure of the health status of noncognitively impaired nursing home residents.

The Sickness Impact Profile (SIP) is a multidimensional, behaviorally based measure of health status that has been successfully used in a wide range of applications. The characteristics of this measure have not been assessed with nursing home residents. The purpose of this study was to assess the feasibility, reliability (internal consistency), validity, and comprehensiveness of the SIP as a measure of the health status of a selected group of nursing home residents. One hundred sixty-eight veterans residing in community and VA nursing homes responded to a questionnaire consisting of the SIP, Index of Activities of Daily Living, Barthel Index, Life Satisfaction Index Z, and the Philadelphia Geriatric Center Morale Scale. In general, the respondents correctly interpreted instructions; reliability and validity were supported; and the SIP was found to provide a comprehensive assessment of physical function. Adding a measure of psychologic well-being to a study protocol involving this population may, however, provide additional useful information regarding this construct.

Issues in the measurement of health status in asthma research.

Asthma is a chronic condition of increasing prevalence and high cost to patients, their families, and society. Research into the causes and consequences of asthma has increased during the last few years, but the use of health status measures to help characterize patient outcomes is infrequent. Those studies that have included health status measures have focused on different dimensions of health status, making comparisons across studies difficult. The purpose of this article is to provide information about the selection of health status measures in studies of persons with asthma and to review applications of and make recommendations for health status assessment in asthma research. These recommendations include: use of both generic and specific instruments where appropriate, the development of new asthma-specific measures and rigorous testing of the several new measures that have been reported recently, and the development and inclusion of utility measures in studies of asthma.