Increased risk for chronic comorbid disorders in patients with inflammatory arthritis: a population based study

Abstract

Background: Studies determining the development of a wide variety of different comorbid disorders in inflammatory arthritis (IA) patients are scarce, however, this knowledge could be helpful in optimising preventive care in IA patients. The aim of this study is to establish the risk that new chronic comorbid disorders in newly diagnosed patients with IA in a primary care setting are developed.

Methods: This is a nested-case-control study from 2001-2010 using data from electronic medical patient records in general practice. In total, 3,354 patients with newly diagnosed IA were selected. Each patient was matched with two control patients of the same age and sex in the same general practice. The development of 121 chronic comorbid disorders of index and control patients was compared using Cox regression.

Results: After a median follow-up period of 2.8 years, 56% of the IA-patients had developed at least one chronic comorbid disorder after the onset of IA, compared to 46% of the control patients (p < 0.05). The most frequent developed comorbid disorders after the onset of IA were of cardiovascular (23%), and musculoskeletal (17%) origin. The highest hazard ratios (HRs) were found for anaemia (HR 2.0 [95% CI: 1.4-2.7]) osteoporosis (HR 1.9 [1.4-2.4]), and COPD (HR 1.8 [1.4-2.3]).

Conclusion: Patients with IA developed more chronic comorbid disorders after the onset of IA than one might expect based on age and sex. Since comorbidity has a large impact on the disease course, quality of life, and possibly on treatment itself, prevention of comorbidity should be one of the main targets in the treatment of IA patients.

Figure 1

Percentage of patients who developed new chronic diseases after inclusion.

Figure 2

The absolute risk on a chronic disease accumulated for the categories no. 1 or 2 and 3 or more diseases. When no bar is presented, the risk for developing a new chronic disease is 0%. Absence of the other two categories means no additional risk with respect to the previous category. For example: a 60-year old male with no additional chronic disease has 2% risk to develop anemia. A 60-year old male with one or two chronic diseases at IA onset has also 2% risk to develop anemia -no additional bar for one or two chronic diseases is presented-. A 60-year old male with three or more chronic diseases at IA onset has 3% risk to develop anemia.

Figure 3

The absolute risk of developing a new chronic disease stacked for the categories no. 1 or 2, and 3 or more diseases. When no bar is presented, the risk for developing a new chronic disease is 0%. Absence of a category means no additional risk with respect to de previous category. For example: a 70-year old female with no additional chronic disease at IA onset has 4% risk to develop COPD. A 70-year old female with one or two chronic diseases at IA onset has 5% risk to develop COPD. A 70-year old female with three or more chronic diseases at IA onset has 6% risk to develop COPD.