Background/Purpose: Chronic comorbid medical conditions may contribute to poor outcomes in rheumatoid arthritis.  The extent of comorbidity, in particular cardiovascular disease (CVD), may  be related to the burden of inflammation and may influence initial treatment choice.  We report the association of baseline comorbidity with clinical disease activity, functional status and quality of life in early inflammatory arthritis (EIA) using data from the Canadian Early Arthritis Cohort (CATCH).

Methods: Subjects (n=779) with EIA of symptom duration 6-52 weeks, ≥ 2 effused joints or1 swollen MCP or PIP and ≥ 2 of: +RF, +CCP, morning stiffness > 45 minutes, response to NSAIDS, or painful MTP squeeze test report comorbid medical conditions at baseline, quality of life indices (SF12) annually, and functional status (HAQ), pain visual analogue scale, detailed arthritis clinical assessments and arthritis treatment at each visit. Although there is no formal treatment protocol, participating rheumatologists aim for minimal disease activity.  The influence of baseline comorbidity on outcomes while controlling for age and disease duration was tested by linear regression.  

Results:  Comorbidity was reported by 538 subjects (69%; median conditions 1 range 0-8).  Patients with vs without comorbidity were older (45 vs 54 years p<0.0001) and had higher baseline disease activity primarily due to ESR (37 vs 21 p<0.001) and CRP (14 vs 11 p<0.02).  Associations between CVD and higher DASCRP3v (4.42(1.3) vs 4.18(1.3) p=0.03) and worse HAQ (1.13(0.73) vs 0.94(0.71) p<0.001) at baseline were not significant after correcting for age. Baseline SF12 scores (all patients) were below population averages (Physical Composite Score (PCS) 37(11) and Mental Composite Score (MCS) 47(12)).  SF12 correlated with the number of comorbidities: PCS (-0.2 p<0.0001) ; MCS (-0.11 p=0.003).  All domain scores were significantly worse in patients with any comorbidity vs without.  Patients with CVD (vs without) (34 (10) vs 38 (11) p<0.0001) endocrine disease (diabetes, thyroid, dyslipidemia) (35(11) vs 38(11) p=0.001), GI or renal (stomach bowel, liver disease, hepatitis or renal; 35(11) vs 38(11) p=0.03) and respiratory (asthma, bronchitis) (p=0.005) had poorer PCS.  Patients with neurologic (migraine, parkinson, seizures) (44(12) vs 47(11) p=0.03), mental health (depression or other)(39 (11) vs 48 (39) p<0.0001) and GI or renal (43(12) vs 47(11) p=0.005) comorbidities were associated with poorer MCS. Patients with any baseline comorbidity had higher DASCRP3v scores (3.15 (8.1) vs 2.94 (9.1) p=0.004), worse functional status (HAQ 0.67 (0.54) vs 0.47 (0.46) p<0.0001), and more pain (3.6 (2) vs 3.2 (2.1) p=0.001), averaged over the first year, than those without baseline comorbidity. Renal or GI disease had worse DASCRP3v (p<0.001) over the first year. Baseline cardiovascular disease was not associated with poorer outcomes.  The number of comorbid conditions at baseline was inversely associated with one year PCS and MCS.

Conclusion: Patients with comorbid medical conditions have greater disease activity, poorer functional status and lower self reported quality of life over the first year of followup.  This observation has implications for treatment of early arthritis.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/self-reported-comorbidity-is-common-in-early-inflammatory-arthritis-and-associated-with-poorer-function-and-quality-of-life-and-greater-disease-activity-results-from-the-canadian-early-arthritis-coho/