LOW-BACK-PAIN AND LIFE-STYLE - PART I - SMOKING - INFORMATION FROM A POPULATION-BASED SAMPLE OF 29,424 TWINS

Study Design. A cross-sectional postal survey of 29,424 people aged 12 -41 years obtained from a population-generated panel of twin individua ls. Objectives. To study whether smoking causes low back pain. Summary of Background Data. Despite insufficient evidence in the epidemiologi c literature, it has become increasingly accepted that smoking causes low back pain and that discontinuation of smoking is a suitable means of secondary prevention. Methods. Dose-response was examined for smoki ng (daily use, number of years smoked, and total cigarette use during the years of smoking) in correlation with low back pain (occurring 1-7 days, 8-30 days, and >30 days in the past year). A possible modifying effect was studied for age, gender, and body mass index. A negative g radient was sought in relation to the time since smoking was discontin ued. The prevalence of low back pain was studied in monozygotic twin p airs, only one of whom smoked. Results. There was a significant positi ve association between smoking and low back pain that increased with t he duration of low back pain: occurring 1-7 days (odds ratio, 1.4), 8- 30 days (odds ratio, 2.1), and more than 30 days (odds ratio, 3) in th e past year. However, these differences in reports of low back pain di sappeared in monozygotic twin pairs discordant on present smoke status . There was no biologic gradient for any of the low back pain definiti ons or measures of smoking-dose, and the prevalence of low back pain d id not decrease with the number of years since smoking was topped. Sma ller people (youngsters, women, people with low body mass index) were not more vulnerable to development of low back pain with smoking. Conc lusions. There is a definite link between smoking and low back pain th at increases with the duration and frequency of the low back pain prob lem, but this link is unlikely to be causal.