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

BACKGROUND CONTEXT: There 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.

PURPOSE: This study aims to investigate the association between obesity and LBP and to investigate the effects of socioeconomic status on this association.

STUDY

DESIGN

This 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 SAMPLE: The sample consisted of 12,862 adults who were aged 18 or older in 2001.

OUTCOME MEASURES: Persons with at least one outpatient or inpatient claim record including 724 as a diagnosis code were defined as LBP patients.

RESULTS

The 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).

CONCLUSIONS

Obesity-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.