Study Design. A prospective, repeated-measures cohort design with high school students from Montreal, Canada.
Objectives. To determine whether smoking was a risk factor for the development of low back pain or other musculoskeletal pain in a cohort of adolescents.
Summary of Background Data. Smoking has been associated with low back pain in adults. Many adolescents smoke, and the prevalence of low back pain in this age group is 30%. A history of low back pain is predictive of future problems.
Methods. A total of 502 students from grades 7 to 9 were assessed from 3 schools. Data were collected at 3 times: at the beginning of the study, at 6 months, and at the end of a 12-month period. Students responded to a questionnaire addressing musculoskeletal health and lifestyle factors, which included smoking. Measurements of height, weight, trunk and leg flexibility, and trunk strength were obtained. Low back pain occurring at a frequency of at least once a week in the past 6 months was defined as the outcome. Multivariate methods were used to model the repeated-measures dichotomous outcome as a function of smoking and other covariates.
Results. Smokers experienced low back pain more than nonsmokers (odds ratio, 2.4; 95% confidence interval, 1.3-6.0). There was also a dose-response relationship between amount smoked and development of low back pain. Smokers tended to experience more upper limb or lower limb pain than nonsmokers, although this result was not significant.
Conclusions. Smoking was found to increase the risk for low back pain in this cohort of adolescents.
In the literature, cigarette smoking in adults is consistently associated with low back pain. 5,6,11,12,14,17,18,23,24,26 Two studies also describe a dose-response relationship between smoking and low back pain. 12,41 In addition, the results of a survey in Norway 6 showed that smoking was significantly associated with musculoskeletal pain in general, whereas a Dutch study 5 showed that smoking was related to back pain only in patients who were employed in more physically exerting occupations.
All of these studies were cross-sectional, and, although they showed an association between low back pain and smoking, it remains unclear whether smoking is an actual risk factor for low back pain. In fact, one investigation of patients with chronic low back pain revealed that patients who smoked reported having a need to smoke when they were in pain. 20
Few longitudinal studies have addressed this subject. One small pilot study done in the United States military found that smokers had an increased risk of low back pain during an 8-week training period. 33 Leino-Arjas 25 reported that smoking was associated with the development of upper and lower limb disorders in individuals who worked in the metal industry.
Evidence from animal models and biologic studies supports an association between smoking and health of the intervertebral disc. Holm and Nachemson 19 found that inhalation of cigarette smoke reduced solute exchange capacity, cellular uptake rate, and metabolite production within the intervertebral discs of pigs, implying a more acute type of mechanism. Battié et al 3 investigated disc degeneration via magnetic resonance imaging in identical twins and found that such degeneration was greater in smokers than in nonsmokers. They found no difference in low back pain between smokers and nonsmokers, however, although it should be noted the statistical power was low in that study.
Although studies consistently have shown an association between smoking and low back pain in adults, few studies have been done to investigate the correlation in adolescents. Low back pain is common in adolescent populations, with reported prevalence proportions ranging between 18% and 35%2,7,29,31,35,38,45 and cumulative annual incidences of 17%32 and 12-21%, 9 depending on age. Furthermore, smoking frequency is increasing, particularly among young girls. 44 Balagué, Dutoit, and Waldburger 2 reported an association between smoking and prevalence of low back pain in adolescents, although the authors themselves doubted the validity of their smoking data, because only 3% or their cohort admitted to smoking. Brattberg 8 found that pupils who smoked at least once a week reported back pain more often than nonsmokers.
The association between smoking and low back pain in adolescents may be extremely important, because a history of low back pain is predictive of future problems. 36 As such, prevention of back pain in youth may contribute to prevention of disability from back pain in adulthood. Therefore, the objectives of this investigation were to determine whether smoking was a risk factor for the development of low back pain or other musculoskeletal pain in a cohort of adolescents. A longitudinal repeated-measures approach was used.