Multimorbidity among incident Finnish systemic lupus erythematosus patients during 2000-2017

Abstract

The objective of the study was to examine the risk of other morbidities among patients with systemic lupus erythematosus (SLE). A total of 1006 adult new-onset SLE patients were identified during 1.1.2000- 31.12.2014 from the register of Social Insurance Institution. For each case three general population controls matched according to age, sex and place of residence at the index day were sampled from the population register. Both groups were followed up from the index date until the end of 2017 or until death. The national register on specialized care was explored to gather broadly their 12 organ-specific morbidities, which were found among 91.2% of SLE patients and 66.7% of comparators. The rate ratio (RR) was elevated in almost all disease groups. Musculoskeletal, cardiovascular and genitourinary conditions were the most common comorbidities with RRs of 1.82 (1.68 to 1.97), 1.91 (1.76 to 2.08) and 1.91 (1.73 to 2.09), respectively. Men with SLE had a significantly higher risk for diseases of the genitourinary system and endocrine, nutritional and metabolic diseases compared to women with SLE. The risk of concurrent morbidities is essential to note in the care of SLE patients.

Keywords: Systemic lupus erythematosus; cardiovascular disease; comorbidity; gender; morbidity.

Figure 1.

Cumulative number of comorbidities among new-onset systemic lupus erythematosus patients diagnosed between 2000–2014 and their controls at the end of the follow-up 2000–2017. Infections and systemic connective tissue diseases are not included.

Figure 2.

Education level adjusted rate ratios of comorbid diseases of systemic lupus erythematosus patients and controls by gender during 2000–2017 and according to 10th revision of the International Classification of Diseases codes. Malignancies = malignant neoplasms C00-D09, Benign neoplasias = benign neoplasms D10–D49, Blood diseases and immune deficiency = disease of the blood and blood-forming organs and certain disorders involving the immune mechanism D50–D89, Endocrinal diseases = endocrine, nutritional and metabolic diseases E00-E90, Psychiatric disorders = mental and behavioural diseases F00–F99, Neurological diseases = diseases of the nervous system G00-G99, Ocular diseases = diseases of the eye and adnexa H00–H59, Cardiovascular diseases = diseases of the circulatory system I00-I99, Asthma and COPD = other chronic obstructive pulmonary disease, asthma and status asthmaticus J44–J46, Inflammatory bowel diseases = noninfective enteritis and colitis K50–K52, Rheumatic diseases and osteoporosis = disease of the musculoskeletal system and connective tissue M00–M99 (excluding systemic connective tissue disorders M30–M36), Genitourinary diseases = diseases of the genitourinary system N00–N99.

Figure 3.

Education level adjusted rate ratios of cardiovascular diseases between systemic lupus erythematosus patients and controls during 2000–2014 according to age at index day. The curves were derived from a four-knot-restricted cubic splines generalized linear models. The models were adjusted for education levels. The grey area represents a 95% confidence interval.