VALIDATION IN LONDON OF A PHYSICAL-ACTIVITY QUESTIONNAIRE FOR USE IN A STUDY OF POSTMENOPAUSAL OSTEOPENIA

Study objective-To determine the validity of a self administered physi cal activity questionnaire to be used as part of a screening device fo r postmenopausal osteopaenia (with additional questions on medical his tory and calcium intake). Design-A questionnaire was posted to 86 peri menopausal women to enquire about weekly hours spent in non-sedentary activity at work, in the household, and during leisure hours. Subjects who returned the questionnaire were visited at home and asked to comp lete a four day activity diary and subsequently to undertake a submaxi mal estimate of VO2 MAX, carried out using a treadmill ergometer. They were interviewed to clarify questionnaire and diary entries. Question naire validity was assessed in comparison with the diary estimates of hours of activity and with VO2 MAX. Participants-A total of 86 perimen opausal women aged 43-54 years were randomly selected from a GP list i n Hammersmith, London. Thirty five women (41%) returned the questionna ire. They were visited at home, given the diary to complete, and invit ed to attend the physiology laboratory for VO2 MAX measurements. Twent y six of the 35 (74%) completed the study and were included in the fin al analysis. Main results-Women spent an average of 51 hours per week in non-sedentary activities. Questionnaire and diary yielded similar r esults (51.05 versus 51.30 h/wk), and there was a good correlation bet ween diary and questionnaire estimates of total weekly hours of non-se dentary activity (r=0.45, p<0.05). Other significant correlations were for standing (r=0.69, p<0.01), leisure activities (r=0.66, p<0.01), a nd for Light household activities (r=0.42, p<0.05). Correlations were better for employed than non-employed subjects. In relation to the dia ry, the questionnaire correctly classified 60% into the top or bottom half of the distribution of activity. Sensitivity and specificity of t he questionnaire were both equal to 61.5%. Conclusions-The questionnai re is useful for classifying subjects according to their level of acti vity, especially when administered in conjunction with an interview. T he four day diary provided a useful reference measure and a focus for discussing activity patterns during an interview related to the questi onnaire responses.