Obesity and knee pain in women

http://www.ncbi.nlm.nih.gov/pubmed/21739621

Arthritis Care Res (Hoboken). 2011 Jul 7. doi: 10.1002/acr.20546. [Epub ahead of print]
Obesity predicts knee pain over 14 years in women, independent of radiographic changes.
Goulston LM, Kiran A, Javaid MK, Soni A, White KM, Hart DJ, Spector TD, Arden NK.
Source
MRC Lifecourse Epidemiology Unit, University of Southampton. lg@mrc.soton.ac.uk.

Abstract
OBJECTIVE:
To examine longitudinal patterns in body mass index (BMI) over 14 years and its association with knee pain in the Chingford Study.

METHODS:
594 women with BMI data from clinic visits at year 1, 5, 10 and 15 were studied. Year 15 (Y15) knee pain was assessed by questionnaire. Associations between BMI over 14 years and Y15 knee pain were examined using logistic regression.

RESULTS:
BMI significantly increased from Y1 to Y15 (p<0.0005) with median (IQR) of 24.5 kg/m(2) (22.5, 27.2) and 26.5 kg/m(2) (23.9, 30.1) respectively. At Y15, 45.1% had knee pain. A greater BMI at Y1 (OR = 1.34, 95% CI 1.05 - 1.69), at Y15 (OR = 1.34, 1.10 - 1.61) and change in BMI over 15 years (OR = 1.40, 1.00 - 1.93) were significant predictors of Y15 knee pain (p<0.05). BMI change was associated with bilateral (OR = 1.61, 1.05 - 1.76), p = 0.024, but not unilateral knee pain (OR = 1.22, 0.73 - 1.76), p = 0.298. The association between BMI change and knee pain was independent of radiographic knee osteoarthritis (RKOA). The strength of association between BMI and Y15 knee pain was similar during follow-up measurements.

CONCLUSION:
Over 14 years, a higher BMI predicts Y15 knee pain in women, independently of RKOA. When adjusted, the association was significant in bilateral, not unilateral, knee pain suggesting alternative pathological mechanisms may exist. The longitudinal effect of BMI on Y15 knee pain is equally important at any time point, which may assist reducing the knee pain population burden.