Use of the SF-12 instrument for measuring the health of homeless persons.

OBJECTIVE: To evaluate the construct validity of the Short Form 12-item Survey (SF-12) among users of a homeless day shelter. Adding brief health assessments has potential to provide information regarding the effect that programs have upon the health status and functioning of homeless persons.

STUDY SETTING: A convenience sample of 145 homeless persons at a day shelter in an urban setting.

STUDY DESIGN: Participants were verbally administered the SF-12 that provides information on mental and physical health status and the Dartmouth Improve Your Medical Care Survey (IYMC) that provides information on functional health, clinical symptoms, medical conditions, and health risk. The IYMC survey system has been widely used in clinical settings to assess health status and the outcomes of care.

DATA COLLECTION/EXTRACTION METHODS: Construct validity was assessed by the following approaches: (a) the method of extreme groups was used where multivariate analysis of variance determined if SF-12 summary scores varied for individuals who differed in self-reported clinical symptoms and medical conditions, and (b) convergent validity was assessed by correlating SF-12 summary scores with the subscales.

PRINCIPAL FINDINGS: Four to 10 point differences in physical health (PCS12) and 5-11 point differences in mental health (MCS12) were found between those who reported acute symptoms and medical conditions and those who did not. A 13-point difference in PCS12 scores and a 7-16-point difference in MCS12 scores were found for those who reported none or few to several symptoms or conditions. The summary scores and subscales yielded satisfactory convergent validity coefficients that ranged from 0.62 to 0.88 with one exception.

CONCLUSIONS: The SF-12 shows promise as a valid outcome indicator for assessing and monitoring health status among the homeless. Its strengths include brevity and availability of norms for specific medical conditions.