[Association between weight-adjusted waist index and pain: A cross-sectional study]

To investigate the relationship between the weight-adjusted waist index (WWI) and acute, subacute pain or chronic pain among American adults.

There was a cross-sectional study. Data from the 1999-2004 National Health and Nutrition Examination Survey (NHANES) concerning waist circumference, weight, pain status and covariates (age, gender, race, marital status, education level and income, physical activity, alcohol consumption, smoking status, and diabetes) were extracted for analysis. Multinomial Logistic regression was conducted across the three models to investigate the associations between WWI and acute, subacute and chronic pain. Model 1 did not involve any adjustments. Model 2 involved adjustments for age, gender, race, marital status, education level, and income. Model 3 was further adjusted for physical activity, alcohol consumption, smoking, and diabetes status.

This study involved 12 694 participants with an average age of (50.6±18.7) years. Among all the participants, 9 614 people (75.74%) had no pain, 870 people (6.85%) experienced acute pain, 354 people (2.79%) suffered from subacute pain, and 1 856 people (14.62%) experienced chronic pain. The WWI of all the participants was (10.95±0.85) cm/$\sqrt{\mathrm{kg}}$, divided into four groups based on quartiles: Group Q1 (7.90-10.36) cm/$\sqrt{\mathrm{kg}}$, group Q2 (10.37-10.94) cm/$\sqrt{\mathrm{kg}}$, group Q3 (10.95-11.53) cm/$\sqrt{\mathrm{kg}}$ and group Q4 (11.54-15.20) cm/$\sqrt{\mathrm{kg}}$. With the increase of WWI, the analysis revealed a significant statistical difference in the participants' acute and chronic pain status (all P < 0.001). In Model 1, the prevalence of acute pain was lower in group Q2 and group Q4 compared with group Q1 (group Q2: OR=0.765, 95%CI: 0.615-0.953, P=0.017; group Q4: OR= 0.648, 95%CI: 0.503-0.835, P < 0.001). Compared with group Q1, the prevalence of chronic pain increased in group Q2, group Q3, and group Q4 (group Q2: OR =1.365, 95%CI: 1.149-1.622, P < 0.001; group Q3: OR=1.291, 95%CI: 1.082-1.541, P=0.005; group Q4: OR=1.874, 95%CI: 1.579-2.224, P < 0.001). In Model 2, compared with group Q1, an increase in chronic pain prevalence was still associated with an increase in WWI in other three groups (group Q2: OR=1.359, 95%CI: 1.137-1.624, P=0.001; group Q3: OR=1.260, 95%CI: 1.039-1.528, P=0.019; group Q4: OR=1.735, 95%CI: 1.413-2.132, P < 0.001). In Model 3, group Q4 had a 49.2% increased prevalence of chronic pain compared to group Q1 (OR = 1.492, 95%CI: 1.208-1.842, P < 0.001). However, in Models 2 and 3, no significant relationship was observed between acute pain and WWI (all P>0.05). And none of the three models identified a significant association between subacute pain and WWI (all P>0.05).

For American adults, there was no significant correlation between WWI and acute pain or subacute pain. However, as WWI increases, so does the prevalence of chronic pain. Further validation of this conclusion through large-scale prospective studies is warranted.