Epidemiology of clinical body mass index recording in an obese population in primary care: a cohort study.

BACKGROUND Protecting and promoting the health of obese people is an important public health concern. This study evaluated the recording of body mass index and medical diagnostic codes for obesity in obese patients in UK primary care. METHODS A cohort study was implemented in the UK General Practice Research Database. Subjects were aged 18-100 years and were diagnosed with obesity between 1997 and 2007. The frequency of obesity monitoring was evaluated. RESULTS There were 67 000 obese patients at 127 family practices. The proportion of obese patients with no annual body mass index (BMI) record reached 65% of men and 63% of women in 2000, declining to 55 and 48% in 2009. Medical diagnostic codes for obesity were infrequently recorded. The mean BMI of obese patients increased to 35.5 kg/m(2) [95% confidence interval (CI): 35.4-35.7] in men and 37.0 kg/m(2) (95% CI: 36.9-37.1) in women by 2009. In 2009, 37% of obese men with BMI records, and 39% of women, showed a BMI increase of ≥1 kg/m(2) since the previous reading. CONCLUSIONS Obese patients do not have BMI values recorded regularly. The mean BMI of obese patients, and the proportion gaining weight over time, is increasing. Improved strategies for monitoring and managing obesity are required.