Functional status, health problems, age and comorbidity in primary care patients.

OBJECTIVES: To determine the relationship between functional status and health problems, age and comorbidity in primary care patients.
METHODS: Patients from 60 general practitioners who visited their general practitioner were recruited and asked to complete a written questionnaire, including a list of 25 health problems and the SF-36 to measure functional status. The response rate was 67% (n = 4,112). Differences between subgroups were tested with p < 0.01.
RESULTS: Poorer functional status which was associated with increased age (except for vitality) and increased co-morbidity. Patients with asthma/ bronchitis/COPD, severe heart disease/infarction, chronic backpain, arthrosis of knees, hips or hands, or an 'other disease' had poorer scores on at least five dimensions of functional status. Patients with hypertension, diabetes mellitus or cancer did not differ from patients without these conditions on more than one dimension of functional status. In the multiple regression analysis age, had a negative effect on functional status (standardised beta-coefficients between -0.03 and -0.34) except for vitality. Co-morbidity had a negative effect on physical role constraints (-0.15) and bodily pain (-0.09). All health problems had effects on dimensions of functional status (coefficients between -0.04 and -0.13). General health and physical dimensions of functional status were better predicted by health problems, age and co-morbidity (between 6.4 and 16.5% of variation explained) than mental dimensions of functional status (between 1.1 and 3.2%).
CONCLUSION: Higher age was a predictor of poorer functional status, but there was little evidence for an independent effect of co-morbidity on functional status. Health problems had differential impact on functional status among primary care patients.