Sun-Protective Behaviors Not Linked to Lower BMD, Fracture Risk

Routine sun-protective behaviors is not associated with decreased bone mineral density (BMD) or increased risk for osteoporotic fracture in adults, according to a study in JAMA Dermatology.

The cross-sectional study analyzed data from the National Health and Nutrition Examination Survey (NHANES) from 2017 to 2018 to determine correlates of sun protection and whether there was an association between multimodal sun-protective behaviors with BMD and the prevalence of osteoporotic bone fractures among US adults.

Sun-protective behaviors included staying in the shade, wearing a long-sleeved shirt, and using sunscreen on a very sunny day.

Investigators included data from 3418 adults aged ≥20 years (average age, 39.5 [95% CI, 38.6-40.4] years; 1806 [52.9%] women) who completed the NHANES dermatology questionnaire. Of this group, 3403 participants had valid answer choices on all 3 sun-protection components of the dermatology questionnaire and were included in the final cohort.

The prevalence of frequent—most of the time or always—staying in the shade was 31.6% (95% CI, 27.8%-35.7%), the prevalence of frequent wearing of long-sleeve clothing was 11.8% (95% CI, 10.6%-13.1%), and the prevalence of frequent use of sunscreen was 26.1% (95% CI, 23.5%-28.8%).

In the multivariate models, the use of individual sun-protective behaviors was not associated with decreased site-specific and total BMD z scores—estimate, −0.23 (95% CI, −0.47 to 0.02), P = .18 for frequent staying in the shade; −0.08 (95% CI, −0.27 to 0.12), P = .72 for frequent wearing of long sleeves; and −0.10 (95% CI, −0.32 to 0.13), P = .15 for frequent sunscreen use.

Multivariate adjustment showed an association of moderate to frequent staying in the shade with a decreased prevalence of osteoporotic spine fractures (0.19 [95% CI, 0.04-0.86]; P = .02).

In addition, statistically significant associations were observed for mild to severe sun sensitivity with reduced odds of wrist fractures (severe sun sensitivity, 0.06 [95% CI, 0.01-0.40]; P = .02) and spine fractures (mild sun sensitivity, 0.08 [95% CI, 0.02-0.34]; P = .01).

Univariate and multivariate analyses found that the use of sunscreen or other sun-protective behaviors was not associated with an increased odds of osteoporotic fractures of any location.

Study limitations include the cross-sectional design of the NHANES 2017 to 2018 dataset, which prevented the researchers from establishing the causality of associations and providing long-term data on participants. Also, the dataset does not clearly distinguish between the use of sunscreens and other sun block products, which may have different potency in various body areas. In addition, BMD scans were done in adults aged ≤59 years, although routine BMD measurements are clinically recommended at about age 65 years.

“The continued practice of sun protection is not associated with increased bone-related health complications such as decreased BMD and/or increased osteoporotic fractures,” stated the investigators. “Sun protection may actually be associated with a modest decrease in the prevalence of osteoporotic fractures, possibly owing to vigilant behaviors, and should be encouraged in all patients, including those otherwise at risk for decreased BMD and fractures.”

Reference

Afarideh M, Sartori-Valinotti JC, Tollefson MM. Association of sun-protective behaviors with bone mineral density and osteoporotic bone fractures in US adults. JAMA Dermatol. Published online October 27, 2021. doi:10.1001/jamadermatol.2021.4143