Impact of pain in overweight to morbidly obese women: preliminary findings of a cross-sectional study.

OBJECTIVES: To evaluate the effect of body mass index (BMI) on the prevalence, intensity and interference of pain in women, and how it affects quality of life and level of physical activity; and to determine independent predictors of pain intensity.

DESIGN: Cross-sectional observational study.

SETTINGS: Obesity treatment clinic, community and university laboratory.

PARTICIPANTS: Seventy-three of 133 women aged 25-75 years reported the presence of pain for at least 2 weeks and were categorised according to BMI (normal weight, overweight, obese or morbidly obese).

MAIN OUTCOME MEASURES: BMI and questionnaires [McGill Pain Questionnaire (MPQ), Brief Pain Inventory (BPI), Short-Form Health Survey-36 (SF-36) and Baecke Physical Activity Questionnaire].

RESULTS: Pain intensity was 3 and 4.5 times higher in the MPQ and BPI, respectively, in morbidly obese women compared with women of normal weight. Morbidly obese women had 10.7 times higher pain interference and lower scores on the SF-36 domains of physical function and role function-physical compared with women of normal weight. Obese and morbidly obese women had less pain relief from treatment. Regression analysis showed that high BMI and low level of physical activity contributed to the intensity of pain, and these variables explained 16% of the variance of pain intensity.

CONCLUSIONS: This study found that the prevalence and intensity of pain are greater in morbidly obese women than women of normal weight, and pain is negatively associated with physical activity. The causal inter-relationships between pain, obesity and physical activity are complex and require further study.