Background/Purpose: To describe the demographic and clinical characteristics of patients with inflammatory arthritis (IA) initiating biologic disease modifying anti-rheumatic drugs (bDMARD) who use complementary and alternative medicine (CAM), and determine the impact of CAM on predicting residual functional disability at six months, as measured by the modified Health Assessment Questionnaire (mHAQ).

Methods: A prospective inception cohort study of all patients ≥ 21 years old initiating a bDMARD for IA after July 2016 was conducted in three public-sector hospitals in Singapore. Baseline and follow-up data were obtained via face-to-face or telephonic questionnaires and abstraction from medical records. Baseline characteristics were compared using chi-square test for categorical variables; and t-test and Wilcoxon signed-rank test for continuous variables in gaussian and non-gaussian distributions respectively. CAM as a predictor of mHAQ ≥ 1 at six months after starting a bDMARD was analysed using multivariate logistic regression, adjusting for other baseline characteristics. Further, interaction of CAM use and smoking was tested.

Results: 299 patients (36.2% males, 70.4% Chinese) of mean (SD) age 49.0 (13.4) years were recruited. 45.8% had rheumatoid arthritis with a mean (SD) Disease Activity Score in 28-joints (DAS-28) of 4.6 (1.2). 54.2% had a spondyloarthropathy with a mean (SD) Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) of 4.7 (2.2). The median (IQR) disease duration was 12.7 (4.7, 38.5) months, with a median (IQR) mHAQ of 0.4 (0.1, 0.9). 93 patients were current or prior CAM users, most commonly acupuncture (64.5%), powder (46.2%), tablets (36.6%), herbs (33.3%), suction (19.4%). Compared to non-users, CAM users had a lower mean body mass index (24.5 vs 26.8kg/m², p=0.002), were less likely to be English-speaking (65.5% vs 85.8%, p< 0.001), more likely to be smokers (28.0% vs 16.7%, p=0.02) and to drink alcohol (33.7% vs 19.6%, p=0.009), and less likely to have cardiovascular disease (2.2% vs 8.8%, p=0.04) (Table 1). Of the 223 patients with 6-month follow-up data, 27.4% were no longer on their index bDMARD. mHAQ was available for 206 patients, median (IQR) 0.1 (0, 0.5), 12.1% with mHAQ ≥ 1. There was no association of CAM use with high mHAQ and no interaction with smoking. Advanced age (odds ratio [OR] < 0.001 [95% CI 5.3E-10 – 0.34]), smoking (OR 938.9 [95% CI 3.20 – 275884.1]), baseline mHAQ (OR 252.2 [95% CI 5.34 – 11899.2]) and Charlson’s Co-morbidity Index (CCI) score of ≥ 4 (OR 237.4 [95% CI 1.22 – 46184.4]) were independent predictors of high mHAQ (Table 2).

Conclusion: CAM use was not associated with high mHAQ at 6 months. Association with advanced age may be attributable to a tendency for elderly patients to under-report scores. Smoking was an independent predictor of residual functional disability at 6 months, even after adjusting for age, comorbidity and baseline mHAQ. More emphasis on smoking cessation may be useful to improve long-term functional outcomes in IA patients on bDMARDs.

* Missing data have been omitted from % calculations. Plus-minus values are means ± standard deviation (SD). + P-values are for differences between CAM users and non-users and were calculated by chi-square test for categorical variables, and by t-test for normally distributed continuous variables and Wilcoxon signed-rank test for non-normally distributed continuous variables. BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; CAM, complementary and alternative medicine; CCI, Charlson’s Co-morbidity Index; DAS-28, Disease Activity Score in 28 joints; IQR, interquartile range; mHAQ, modified Health Assessment Questionnaire; TNFi, tumour necrosis factor inhibitor.

Variables were included in the multivariable model if they were significant at P ≤ 0.2 on univariate analysis. † Not included in the multivariable model due to collinearity with mHAQ. ‡ Hypertension and hyperlipidemia were statistically significant in the univariate analysis as well, but not included in the multivariate model due to collinearity with CCI. BASDAI, Bath Ankylosing Spondylitis Disease Activity Index; CAM, complementary and alternative medicine; CCI, Charlson’s Co-morbidity Index; DAS-28, Disease Activity Score in 28 joints; mHAQ, modified Health Assessment Questionnaire; TNFi, tumour necrosis factor inhibitor.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/smoking-but-not-use-of-complementary-and-alternative-medicine-predicts-residual-functional-disability-in-patients-with-inflammatory-arthritis-on-biologic-disease-modifying-anti-rheumatic-drugs-resul/