Quarter of Arthritis Cases Linked to Weight.

A new School of Public Health study shows that weight loss between early adulthood and midlife lowers arthritis risk, and found no evidence of any persistent risk of arthritis for people who were heavier earlier in life and then lost weight.

The study, published in the journal Arthritis Care & Research, also estimates that nearly a quarter of arthritis cases in the US, corresponding to 2.7 million people, are attributable to weight.

“Policies that address the social and structural factors that promote weight gain are urgently needed. Our findings suggest that such measures could have a significant impact on reducing the incidence of arthritis, a leading cause of disability and chronic pain in the US,” says study corresponding author Andrew Stokes, assistant professor of global health.

“Although weight loss could represent a viable way to reduce arthritis risk at the individual level, we found that the best solution at the population level would be to prevent weight gain,” says study lead author Kaitlyn Berry (SPH’17), who was a research fellow at SPH while working on the study and is now at the University of Minnesota School of Public Health.

The researchers used data from the National Health and Nutrition Examination Survey (NHANES) on adults 40-69 years old, to categorize individuals based on the changes in their body mass indices (BMI) from early adulthood to mid-life, and analyzed the association between these BMI trajectories and the risk of developing an arthritis condition within 10 years.

Of the 13,669 people in the study, 3,603 developed an arthritis condition. Compared with those who had a BMI in the “normal” range in both early adulthood and middle age, those who went from the “normal” range to the “overweight” or “obese” ranges, those who went from the “overweight” range to the “obese” range, and those whose BMIs were in the “obese” range at both points were all significantly more likely to develop arthritis conditions.

On the other hand, those whose BMIs went from the “obese” down to the “overweight” range had a significantly lower risk of developing arthritis compared to those whose BMI remained in the “obese” range. Additionally, those who lost weight had the same likelihood of developing arthritis as those whose BMIs stayed in the “overweight” range.

“These findings highlight the need for lifelong public health measures to prevent obesity at younger ages as an important step to curb later life musculoskeletal and joint health problems such as osteoarthritis. This is particularly important as musculoskeletal pain is a leading cause of disability globally,” says study co-author Tuhina Neogi, professor of epidemiology at SPH, professor of medicine at the School of Medicine, and chief of rheumatology at Boston Medical Center.

The study was co-authored by Michael P. LaValley, professor of biostatistics. The other co-authors are Joshua F. Baker of the University of Pennsylvania; Jason M. Collins of the University of North Carolina Gillings School of Global Public Health; Jason R. Waggoner and  Chia‐Wen Hsiao of Ethicon, Inc.; and Stephen S. Johnston of Johnson & Johnson.

—Michelle Samuels