Sub-health and health-related quality of life

Abstract

Sub-health has been used to describe an intermediate state between health and disease. The impact of SH on HRQOL deserves more attention because HRQOL is an important goal of health care, and a significant determinant of health service utilization. The aim of this study was to establish the epidemiology of Sub-health and explore the relationship between SH and HRQOL. Two studies were conducted in Hong Kong. The first study was to develop and validate a Sub-health questionnaire (SHQ) for classifying people into Health, SH & Disease. The standard 7-step method of development of a psychometric measure was used to develop the SHQ. The initial SHQ, was then field tested on a sample of 13 Chinese adults. Pilot testing of the final version was conducted on 55 Chinese adults to confirm. Psychometric testing by a longitudinal survey on 353 Chinese adults who completed the SHQ, the SF-12v2 Health Survey and a structured questionnaire on sociodemographic data, and health service utilization at baseline, 2 to 4 weeks and 3-month. All HS items had Content Validity Index (CVI) on clarity and relevance of > 75%. The HS items demonstrated good internal consistency (Cronbach’s alpha=0.82). The overall test-retest reliabilities of classification of the health state were moderate with Kappa > 0.57. The SHQ was responsive in detecting a change in health states in 36.4% subjects in 3 months. Item scores of HS scales had significant correlation (r>0.4) with corresponding SF-12v2 scores, and there were significant differences in SF-12v2 summary scores between SHQ groups. The second was a longitudinal study on Sub-health and HRQOL of general population to evaluate the validity and psychometric property of SHQ, to establish determine the epidemiology SH, and to explore the relationship between HRQOL of SH. 1231 Chinese adults were randomly selected from the general population by telephone survey with the SHQ, SF-12 Health Survey and a structured questionnaire on demographics and service utilization. 353 subjects had completed 3 to 12 months follow up surveys. The prevalence of Sub-health is 40.67% in Hong Kong. There were significant differences in SF-12v2 scores in that SH group had higher scores than those of disease group but lower scores than those of health group. SH was associated with higher use of medical resources than health. Conclusively, the SHQ is a useful screening tool for the diagnosis of SH. There is a linear relationship between change in health status and changes in HRQOL or health service utilizations. It preliminary explored the clinical relevance of the SH to a culture and health care system that is different from that of mainland China where the concept originated. The results would be useful in populations worldwide if the SHQ could be cross-culturally adapted to identify the SH epidemiology. The study has also, provided evidence supporting the conceptual base of SH in the Chinese medicine context, which may be modifiable by treatment based on TCM Body Constitution classification.