Normative Reference Values for Composite Physical and Mental Health Scores Derived from the SF-36 in Brazilian Community-Dwelling Older Adults

Abstract

Background: Due to the global increase in life expectancy, the assessment of health-related quality of life (HRQoL) has become essential for evaluating healthy aging and guiding clinical decision-making. Although the SF-36 is one of the most widely used HRQoL instruments, sex- and age-specific reference values for its composite physical and mental health scores in older adults remain limited. Objective: To develop sex- and age-specific reference values for the physical and mental health composite scores derived from the SF-36 and to establish a global health-related quality of life index in Brazilian community-dwelling older adults. Methods: This longitudinal observational study included 420 community-dwelling older adults from Brazil. Participants underwent assessments of physical and functional fitness (IAFG-6), sociodemographic characteristics, comorbidities, and health-related quality of life. Sex- and age-specific reference values were generated using percentile distributions, allowing classification into three categories: low, intermediate, and good quality of life. The applicability of the proposed classification was examined through its association with functional status assessed using the IAFG-6. Results: Quality-of-life scores differed significantly across sex- and age-specific groups for the physical health composite, mental health composite, and overall health-related quality of life indicators (p<0.001, p=0.040, and p<0.001, respectively). Better functional status was significantly associated with higher classifications of physical health (p<0.01), mental health (p<0.05), and overall health-related quality of life (p<0.01), providing evidence supporting the construct validity of the proposed reference values. Conclusion: This study established sex- and age-specific reference values for the physical and mental health composite scores derived from the SF-36 in Brazilian community-dwelling older adults. The results demonstrated significant differences in quality-of-life scores according to sex and age group, particularly for the physical health component, with men presenting higher scores than women. These findings provide population-specific reference values that may support the interpretation of SF-36 composite scores in older adults with characteristics similar to those of the study population. Future studies involving larger and more geographically diverse samples are needed to validate and expand these reference values.