Chronic back pain (CBP) is a worldwide health problem. Recent evidence points to the coexistence of CBP with other comorbidities, configuring a scenario of multimorbidity. However, the impact of multimorbidity on patients with CBP is still unclear.

To investigate existing differences in levels of activity limitation due to CBP, self-rated health status and use of health services among adults with CBP with and without multimorbidity.

Cross-sectional study with data from adults (≥18 years) who self-reported having CBP (n=18930) in the National Health Survey 2019. Multimorbidity was defined by the presence of one or more chronic diseases in addition to CBP. Data related to sociodemographic variables (gender, body mass index (BMI)), activity limitation (scale 1-5 points: “not limit” =no limitation and “little”, “moderate”, “intense” and “very intense” = with limitation), self-rated of health status (scale 1-5 points: “very good”, “good”, “regular” = positive perception and “poor” and “very poor” = negative perception), use of health services in the last 15 days and of hospitalization in the last 12 months (yes or no) were collected. Differences in proportions (SD) between groups and respective confidence intervals (95%CI) were calculated for sociodemographic and health indicators. Chi-square test was used to determine significant differences (p > 0.05) between groups.

Of the total 18930 adults with CBP, 12,832 (69.4%) reported having multimorbidity. Most adults with CBP and multimorbidity were women (SD=19.4%, 95%IC 17.9-20.89) people with obesity (BMI>30kg/m2) (SD=11.3%, 95%CI: 10.04-12.55), higher activity limitation (SD=14.4%, 95%CI:12.93-15.86), worse health status (SD=10,3%, 95%CI: 9.4;11.2), higher use of health services in the last 15 days (SD=17.1%, 95%CI: 15.7-18.4) and more frequent hospitalization in the last 12 months (SD=6.4%, 95%CI: 5.6-7.2 ) when compared to adults with CBP but without multimorbidity.

About 7 out of 10 adults with CBP have multimorbidity. Adults with CBP and multimorbidity are mostly women, usually obese, reported having more activity limitations, worse health status and recently seeking care at health services.

Multimorbidity is prevalent in the CBP population and must be considered during evaluation and treatment.