Associations among low back pain, income, and body mass index in Taiwan

Background contextThere is a lack of literature on the association of obesity with low back pain (LBP) in oriental countries. Furthermore, no research has explored whether higher socioeconomic status cushions obesity-related risk of LBP.PurposeThis study aims to investigate the association between obesity and LBP and to investigate the effects of socioeconomic status on this association.Study designThis was a retrospective cohort study using data from Taiwan's 2001 National Health Interview Survey and 2002 to 2004 National Health Insurance claim records.Patient sampleThe sample consisted of 12,862 adults who were aged 18 or older in 2001.Outcome measuresPersons with at least one outpatient or inpatient claim record including 724 as a diagnosis code were defined as LBP patients.ResultsThe estimated risk levels of being overweight (23.0≤body mass index [BMI]<25.0) and of being in Class I of obesity (25.0≤BMI<30.0) were the same (hazard ratio [HR]=1.31), and no statistically significant difference in risk level was detected among persons with different economic levels. Among people in Class II of obesity (BMI≥30.0), the LBP risk levels were different for persons with an economic level in the bottom quintile (defined as the poor) and their better-off counterparts (HR=1.77 vs. 1.24, p<.05).ConclusionsObesity-related risk of LBP is substantially higher for poor people than for those with higher socioeconomic status. Weight reduction should be promoted as a way to reduce LBP. Because income may serve as a proxy for other variables, the mechanisms underlying the empirical observed associations need to be further explored.