Older Subjects without Radiographic Knee Osteoarthritis: Weight, Height, and Body Mass Index.

mostly female (72%), all Caucasian, better educated than the average US citizen, and more subjects lived with others. At all three life-stages, weights and BMI were lower, while heights were comparable to US 2000 figures. BMI was in the "normal" category at age 25 and in the "overweight" category at age 78. Weight was under reported and height was over reported, but by less than the general population. Both the increase in weight and decrease in height with age were statistically significant. Absence of RKOA appears to be related to lower weights, average heights, and lower BMI, relative to population norms at all three life-stages. These findings also suggest that the relationship may be more complicated. Higher BMI is ubiquitously recognized as a risk factor for RKOA, yet the average BMI of the subjects without RKOA was in the "overweight" category at age 78. A possible explanation may be an "inflated" BMI based on decrease in height, not just increase in weight.