The Effect of Cigarette Smoking on the Development of Osteoporosis and Related Fractures

, Department of Orthopaedic Surgery, University of Pittsburgh, Pittsburgh, Pa.

Disclosures

Medscape General Medicine. 1999;1(3) 

In This Article

Abstract and Introduction

Abstract

Currently, 25% of the adult population in the United States smoke cigarettes. By the age of 80 years, axial and appendicular bone mineral density will be, on average, 6% to 10% lower in these individuals compared with never-smokers. This decreased density translates into a doubling of risk for spine fractures and a 50% increase (range, 20% to 100%) in risk for hip fracture. One in eight hip fractures in women is attributable to long-term cigarette use. Fracture healing is delayed in smokers, and malunion and nonunion occur more frequently. Although much of the research to date has focused on female smokers, the limited data available on men suggest that the adverse effects of smoking on bone health are similar in both men and women.

The effects of smoking on bone are cumulative and currently cannot be detected until after menopause in women or after the age of 60 years in men. Cigarette smoking shows a dose-response relationship to bone health, with heavier smokers having lower bone density and a higher risk for fracture. The data for former smokers are intermediate between never-smokers and current smokers, indicating that cessation of smoking may slow or prevent further bone loss.

The mechanism of action of smoking on bone is unclear. Although smokers are thinner and exercise less and females who smoke have earlier menopause (all of which are associated with lower bone density), smoking appears to have other independent effects on bone. It is postulated that the antiestrogenic effects of smoking may play a key role in both men and women.

Introduction

Cigarette smoking has toxic effects on most systems and tissues in the body, and life expectancy among smokers in this country is, on average, 5 to 10 years less than that of nonsmokers.[1,2,3] The influence of smoking on the development of cardiovascular and pulmonary diseases and the established links to carcinogenesis have been recognized for many years.[1,3] Additionally, long-term cigarette use is associated with increased bone loss and leads to osteoporosis, fractures, and dental and periodontal disease.[4,5,6,7,8,9]

The lifetime prevalence of smoking in the United States has declined since the 1970s, but even now about 25% of the adult population smoke cigarettes. Young women are smoking at increasingly earlier ages, and the prevalence of cigarette use in high school is higher among girls than boys.[10] Women are less successful than men in their attempts to quit smoking. Among those who do not complete high school, one third or more regularly smoke cigarettes. These behaviors have significant future health implications because individuals who begin to smoke at an early age are less likely to stop.[10]

The clinical signs and symptoms of smoking-related diseases typically become evident in middle-aged and elderly patients, usually decades after their first cigarette. Smoking is known to have systemic antiestrogen effects and other endocrine influences in the body. It is hypothesized that the effects of smoking on bone may begin in adolescence, resulting in lower than normal peak bone mass and smaller bone size.[11,12] The age-related bone losses that occur in both men and women in the fifth decade of life and thereafter also appear to be accelerated among smokers.[13,14,15] For women, bone loss occurs rapidly in the perimenopausal and postmenopausal years when endogenous estrogen levels decrease abruptly in women. Smoking augments this process.[5,16,17] The net result is lower bone mass in older smokers compared with nonsmokers, causing decreased bone strength and increased incidence of fractures (Figure 1).[7,8,13,18,19,20,21] In addition, fracture healing also appears to be impaired in smokers.[22,23,24,25,26,27,28,29]

Figure 1. Relationship of chronic cigarette use to bone strength and fractures.

Although most evidence confirms the adverse effects of cigarette use on bone metabolism, there are some studies that suggest that this association is spurious.[21,30,31,32,33,34] These paradoxical findings may be related to demographic and lifestyle differences between smokers and nonsmokers. For instance, smokers are usually thinner, are more sedentary than nonsmokers, and undergo menopause at a younger age. All these factors are associated with lower bone mass. In addition, smokers are more likely to use alcohol than nonsmokers; moderate alcohol use is associated with higher than usual bone mass, whereas long-term excessive alcohol intake is associated with decreased bone mass. Therefore, clinical research studies on the effects of smoking on bone must control for such potential confounders.[11]

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