Assessing Measurement Properties of Two Single-item General Health Measures

Abstract

Multi-item health status measures can be lengthy, expensive, and burdensome to collect. Single-item measures may be an alternative. We compared measurement properties of two single-item, general self-rated health (GSRH) questions to assess how well they captured information in a validated, multi-item instrument. We administered a general health survey (SF-12V) that included "standard" and "comparative" forms of a GSRH. We repeated the survey two weeks later to the same 75 medically stable outpatients to test for GSRH reproducibility, reliability, and validity using SF-12V Physical Functioning and Emotional Health subscales as a reference. At each survey administration, the two GSRH questions demonstrated good alternate forms reliability (first administration: r = 0.74, p < 0.001; second administration: r = 0.74, p < 0.001) and good reproducibility ("standard": ICC 0.69; "comparative": ICC 0.85). Both GSRH items correlated with physical functioning ("standard": r = 0.66; "comparative": r = 0.56) and emotional health measures ("standard": r = 0.65; "comparative": r = 0.59). Mean subscale measures associated with responses in each GSRH category were significantly different (ANOVA, p < 0.001), indicating strong discriminant scale performance. Our single-item, GSRH questions demonstrated good reproducibility, reliability, and strong concurrent and discriminant scale performance with an established health status measure.