Elsevier

Injury

Volume 46, Issue 7, July 2015, Pages 1333-1340
Injury

Cigarette smoking and risk of hip fracture in women: A meta-analysis of prospective cohort studies

https://doi.org/10.1016/j.injury.2015.04.008Get rights and content

Abstract

Background and objectives

Whether cigarette smoking can increase the risk of hip fracture in women is unclear. This meta-analysis, which pooled results from 10 prospective cohort studies, was performed to derive a more precise estimation between cigarette smoking and the risk of hip fracture in women.

Materials and methods

Pubmed, Cochrane Central Register of Controlled Trials and ISI Web of Science were systematically searched to identify relevant studies. A meta-analysis was performed to examine the association among 10 studies. The pooled risk estimates were calculated by using both random- and fixed-effects model. Heterogeneity among articles and their publications bias were also tested. All of the statistical analyses were performed using the software programs STATA (version 12.0).

Results

Relative risk was significantly increased in current female smokers (pooled RR, 1.30; 95%CI, 1.16–1.45). The association was significant among the high-dose smokers (more than 15 cigarettes per day) while not among the low-does smokers (less than 15 cigarettes per day). Omission of any single study had little effect on the pooled risk estimate. Former smokers had a similar RR of hip fracture (RR, 1.02; 95%CI, 0.93–1.11) to published papers. Smoking cessation for ≥10 years leads to a significant decline in risk.

Conclusions

Smoking is associated with an increased hip fracture risk in women. Cessation of smoking for ≥10 years had a decreased impact on risk of hip fracture. Given the inconsistency among the studies in the choice of adjustments, the associations between cigarette smoking and risk of hip fracture in women await further investigation.

Introduction

Hip fracture is the most frequent and severe fracture in old person, which is associated with substantial morbidity and mortality [1], [2], [3], [4]. One-year and 2-year mortality rates after hip fracture surgery were 14.7% and 24.3%, respectively [3]. 19–37% of the hip fractures in women have been estimated to be caused by tobacco smoking [5], [6].

Several mechanisms may be involved in the harmful effect of hip fracture, including earlier onset of menopause [7], [8], unhealthy and sedentary lifestyle, changes of serum estradiol levels [9], serum parathyroid level [10], [11] serum vitamin D level [12], reduction of oestrogen production and enhancement of the hepatic metabolism of estradiol [9], and so on.

Currently, the association between cigarette smoking and risk of hip fracture in women remains unclear. There have been conflicting views from different studies [5], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23]. Some researches demonstrated a positive association between cigarette smoking and hip fracture [5], [13], [16], [17], [19], [20], [21], [23], whereas others failed to show such a relationship [14], [18], [22]. Two meta-analyses supported the positive view [6], [24]. However, most of the included articles were cross sectional studies and case–control studies. As we know, case–control studies and cross sectional studies are prone to generate bias. In 2005 Kanis et al. [25] performed another Meta analysis demonstrating the association of cigarette smoking and hip fractures, including men and women. In this study, we assess the associations between cigarette smoking and hip fractures only in women. In addition, we also examine dose-response and time since smoking cessation which other meta-analyses did not.

Due to conflicting conclusions of individual literatures, we performed a meta-analysis of prospective cohort studies to assess the associations between cigarette smoking and hip fractures in women. We hypothesized that there is a positive relationship between cigarette smoking status and risk of hip fracture in women.

Section snippets

Literature search

We conducted a meta-analysis of prospective cohort studies that evaluated the association between cigarette smoking and risk of hip fractures in women. We attempted to follow the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines in the report of our meta-analysis [2], [26]. On January 1, 2014, a systematic search of Pubmed, Cochrane Central Register of Controlled Trials and ISI Web of Science was performed. The search terms were shown in Table 1. Reference lists of

Literature search

This search identified 6315 candidate publications. Most of them were excluded because of duplications or nonrelevance or because they were not prospective cohort studies. After assessing the full-text of the 21 potentially relevant articles, 10 publications met the inclusion criteria [5], [13], [14], [15], [16], [17], [18], [19], [20], [21]. The main reasons for exclusion were as follows: one paper was duplicate report of another paper from the same study so the older one was excluded [5], [30]

Discussion

This meta-analysis of 10 prospective cohort studies suggests a significant positive association of current cigarette smoking with risk of hip fracture (current versus never smoking RR, 1.30; 95%CI, 1.16–1.45; current versus nonsmoking RR, 1.54; 95%CI, 1.20–1.87). Furthermore, the association is strengthened by dose-response analysis, with stronger associations for high-dose smokers relative to low-does smokers. Our analyses also show a similar risk of former smokers compared with never smokers

Conclusions

In conclusion, findings of this meta-analysis of prospective cohort studies show that current women smokers, especially high-dose smokers, have a significantly increased risk of hip fracture. The difference of risk of hip fracture seems to be not significant between female former smokers and never smokers. These results strongly indicate that cigarette smoking in women is related to hip fracture. In addition, smoking cessation for ≥10 years of women had an inverse impact on risk of hip

Conflict of interest

The authors declare no conflict of interest.

There are no potential conflicts of interest include employment, consultancies, stock ownership, honoraria, paid expert testimony, patent applications/registrations, and grants or other funding.

References (44)

  • L. Briongos et al.

    Treatment of osteoporosis and hip fractures in a Spanish health area

    Eur Rev Med Pharmacol Sci

    (2013)
  • S. Hoidrup et al.

    Tobacco smoking and risk of hip fracture in men and women

    Int J Epidemiol

    (2000)
  • M.R. Law et al.

    A meta-analysis of cigarette smoking, bone mineral density and risk of hip fracture: recognition of a major effect

    BMJ

    (1997)
  • M. Sneve et al.

    The association between serum parathyroid hormone and bone mineral density, and the impact of smoking: the Tromsø Study

    Eur J Endocrinol

    (2008)
  • I. Kato et al.

    Diet, smoking and anthropometric indices and postmenopausal bone fractures: a prospective study

    Int J Epidemiol

    (2000)
  • A. Paganini-Hill et al.

    Exercise and other factors in the prevention of hip fracture: the Leisure World Study

    Epidemiologist

    (1991)
  • H.E. Meyer et al.

    Risk factors for hip fracture in middle-aged Norwegian women and men

    Am J Epidemiol

    (1993)
  • L. Forsen et al.

    Interaction between current smoking, leanness, and physical inactivity in the prediction of hip fracture

    J Bone Miner Res

    (1994)
  • S.R. Cummings et al.

    Risk factors for hip fracture in white women. Study of Osteoporotic Fractures Research Group

    N Engl J Med

    (1995)
  • L. Forsen et al.

    Ex-smokers and risk of hip fracture

    Am J Public Health

    (1998)
  • A.H. Holmberg et al.

    Risk factors for hip fractures in a middle-aged population: a study of 33,000 men and women

    Osteoporos Int

    (2005)
  • J. Robbins et al.

    Factors associated with 5-year risk of hip fracture in postmenopausal women

    JAMA

    (2007)
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    These authors contributed equally to this work.

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