Smoking and osteoporosis

There is a significant reduction in bone density of women who smoke compared with women who smoke less or not at all.

Premenopausal women smokers have normal oestrogen concentrations but increased concentrations of sex hormone binding globulins and increased 2-hydoxylation of oestradiol to 2-hydroxyoestradiol.

The most common sites to be affected by osteoporosis in smokers are the spine and the distal radius (generally regarded as being more sensitive to oestrogen) (1).

Smokers, in general, enter menopause 1-2 years earlier than non-smokers (1). Smoking also is related to an increase in loss of bone density in middle-aged men compared with non-smokers.

The effect of smoking on bone loss is a dose-related (1).

One non-systematic review and meta-analysis of 10 large prospective cohort studies (random population samples) from USA, Canada, Japan and Europe included 59,232 men and women (74% female) and 250,000 patient-years of follow up

• found that current smoking was associated with a significantly increased risk of any kind of fracture
• risk was greater in men than women
• adjustments for BMD and BMI slightly reduced the risk ratio as smokers tend to be lighter than non-smokers
• for all fractures, the unadjusted relative risk associated with current smoking was 1.25 (95% CI 1.15 to 1.36). The relative risk adjusted for BMD was 1.13 (95% CI, 1.01 to 1.25). For osteoporotic fractures, unadjusted relative risk was 1.29 (95% CI 1.17 to 1.43) and adjusted for BMD was 1.13 (95% CI 1.00 to 1.28). The highest risk was observed for hip fracture (RR 1.84, 95% CI 1.53 to 3.33) with slightly lower risk after adjustment for BMD (RR 1.6, 95% CI 1.27 to 2.02)

Smokers over the age of 50 should be considered for fracture-risk assessment, particularly in the presence of other risk factors (3)
Smokers should be advised to stop smoking to reduce their risk of fragility fracture (3)

Reference:

• Editorial. NEJM 1994, 330, 430-1.
• Law MR, Hackshaw AK. A meta-analysis of cigarette smoking, bone mineral density and risk of hip fracture: recognition of a major effect. BMJ 1997;315(7112):841-6.
• SIGN (June 2020). Management of osteoporosis and the prevention of fragility fractures