Pain in itself cannot be associated with premature mortality in patients with psoriatic arthritis (PsA), according to research results published in Rheumatology.
To determine if higher cumulative pain intensity scores are associated with excess mortality risk in people with PsA, researchers conducted a nested case-control study using data from the nationwide DANBIO registry. The DANBIO registry was established in Denmark in 2000 and includes prospective data for more than 8000 patients with PsA treated in outpatient clinic settings.
The total cohort included 276 patients matched with 1187 control group participants (4.3 control group participants per case).
Patients had more average clinic visits (7 vs 3), a higher pain average (46 vs 37), and were more likely to be taking biologic disease-modifying antirheumatic drugs (bDMARDs) and glucocorticoids compared with matched control group participants. These patients also had lower recorded income and education levels, and were more likely to have comorbid diabetes, chronic obstructive pulmonary disease, cardiovascular disease, and/or cancer.
Results of a crude conditional logistic regression analysis demonstrated a statistically significant association between average Visual Analog Scale (VAS) pain intensity and mortality (odds ratio [OR], 1.06; 95% CI, 1.02-1.10 per every 5 VAS unit increase). When adjusting for additional confounders, this association was attenuated.
In a secondary analysis, where only the average pain for the most recent 1 year and 5 years was investigated, similar results were demonstrated (OR, 1.06 for both); these associations were also attenuated following adjustment for additional confounders.
Results of the complete case analysis showed an association between pain intensity and mortality in the crude analysis (OR, 1.07), but no associations in either models 1 or 2 (OR 0.97 and 0.96, respectively). Findings were not altered when the Health Assessment Questionnaire-Disability Index (HAQ-DI) was omitted from the models.
When average pain intensity was used as a categorical variable, it resulted in an increased likelihood of mortality for patients with average pain intensities of 34 to 66 on the VAS scale, compared with pain levels of 0 to 33 in the crude model.
Study limitations include data being unavailable that would make diagnoses of fibromyalgia or widespread pain possible and a large proportion of data being missing, making it impossible to include smoking status or body mass index in the analysis.
“The current study is the first large-scale national cohort study to examine pain intensity and early mortality in patients with PsA,” the researchers concluded. “These results indicate that pain intensity has limited predictive value for preterm or excess mortality whereas recent glucocorticoid use, chronic pulmonary disease, diabetes, cancer, and cardiovascular disease were all associated with an increased risk of early death.”
Vela J, Cordtz RL, Kristensen S, et al. Is pain associated with premature mortality in patients with psoriatic arthritis? a nested case-control study using the DANBIO Register. Rheumatology (Oxford). Published online March 1, 2021. doi:10.1093/rheumatology/keab192