Multimorbidity in Antineutrophil Cytoplasmic Antibody-Associated Vasculitis: Results From a Longitudinal, Multicenter Data Linkage Study.

OBJECTIVE: Antineutrophil cytoplasmic antibody-associated vasculitis (AAV) is considered a chronic, relapsing condition. To date, no studies have investigated multimorbidity in AAV nationally. This study was undertaken to characterize temporal trends in multimorbidity and report excess health care expenditures associated with multimorbidities in a national AAV cohort from Scotland. METHODS: Eligible patients with AAV were diagnosed between 1997 and 2017. Each patient was matched with up to 5 general population controls. Linked morbidity and health care expenditure data were retrieved from a Scottish national hospitalization repository and from published national cost data. Multimorbidity was defined as the development of ≥2 disorders. Prespecified morbidities, individually and together, were analyzed for risks and associations over time using modified Poisson regression, discrete interval analysis, and chi-square test for trend. The relationship between multimorbidities and health care expenditure was investigated using multivariate linear regression. RESULTS: In total, 543 patients with AAV (median age 58.7 years [range 48.9-68.0 years]; 53.6% male) and 2,672 general population controls (median age 58.7 years [range 48.9-68.0 years]; 53.7% male) were matched and followed up for a median of 5.1 years. AAV patients were more likely to develop individual morbidities at all time points, but especially <2 years after diagnosis. The highest proportional risk observed was for osteoporosis (adjusted incidence rate ratio 8.0, 95% confidence interval [95% CI] 4.5-14.2). After 1 year, 23.0% of AAV patients and 9.3% of controls had developed multimorbidity (P < 0.0001). After 10 years, 37.0% of AAV patients and 17.3% of controls were reported to have multimorbidity (P < 0.0001). Multimorbidity was associated with disproportionate increases in health care expenditures in AAV patients. Health care expenditure was highest for AAV patients with ≥3 morbidities (3.89-fold increase in costs, 95% CI 2.83-5.31; P < 0.001 versus no morbidities). CONCLUSION: These findings emphasize the importance of holistic care in patients with AAV, and may identify a potentially critical opportunity to consider early screening.

Risk of opportunistic infections in patients with antineutrophil cytoplasmic antibody-associated vasculitis, using a Japanese health insurance database.

AIM: Opportunistic infections (OIs) adversely affect outcomes in patients with antineutrophil cytoplasmic antibody-associated vasculitis (AAV). This study aimed to identify the incidence proportion of risk factors for OIs in patients with AAV who were on remission-induction therapy, using a Japanese health insurance database. METHOD: This retrospective longitudinal population-based study was conducted using claims data provided by Medical Data Vision Co., Ltd. We defined individuals as AAV cases receiving remission-induction therapy if they met all of the following criteria: (a) having OIs with at least 1 specified International Statistical Classification of Diseases and Related Health Problems, 10th Revision code (M300, M301, M313, or M318); (b) receiving at least 1 prescription of oral corticosteroids (CS) with prednisolone (PSL)-equivalent dosage ≥30 mg/d, CS pulse therapy, immunosuppressive agents or rituximab during hospitalization between April 2008 and April 2017; and (c) at least 7 days of hospitalization while on the above-mentioned therapies. We calculated incidence and proportion of OIs during the year following remission-induction therapy and the adjusted odds ratio (OR) using a logistic regression model. RESULTS: We included 2299 patients with AAV in this study. OIs occurred in 460 patients (20.0%), with the most frequently occurring OI being cytomegalovirus infection (n = 122, 6.5%). After adjusting for covariates, age by decade (OR 1.24, 95% CI: 1.12-1.36), daily PSL dose per 10 mg (OR 1.16, 95% CI: 1.08-1.25), and CS pulse therapy (OR 1.29, 95% CI: 1.04-1.60) were found to be significantly associated with occurrence of OIs. CONCLUSION: Older age and corticosteroid use were found to be significant risk factors for OIs in patients with AAV on remission-induction therapy, using a health insurance database.

Alternative population sampling frames produced important differences in estimates of association: a case-control study of vasculitis.

OBJECTIVE: A common population sampling frame in countries with universal health care is health service registers. We have evaluated the use of such a register, in the United Kingdom, against a commercially available database claiming large population coverage, an alternative that offers ease of access and flexibility of use. STUDY DESIGN AND SETTING: A case-control study of vasculitis, which recruited cases from secondary care clinics in Scotland, compared two alternative sampling frames for population controls, namely the registers of National Health Service (NHS) primary care practices and a commercially available database. The characteristics of controls recruited from both sources were compared in addition to separate case-control comparison using logistic regression. RESULTS: A total of 166 of 189 cases participated (88% participation rate), while both the commercial database and NHS Central Register (NHSCR) controls achieved a participation rate of 24% among persons assumed to have received the invitation. On several measures, the NHSCR patients reported poorer health than the commercial database controls: low scores on the physical component score of the Short Form 36 (odds ratio [OR]: 2.3; 95% confidence interval [CI]: 1.3-4.1), chronic widespread pain (OR: 2.3; CI: 1.1-4.7), and high levels of fatigue (OR: 2.0; CI: 1.3-3.1). These had an important influence on the estimates of association with case status with one association (pain) showing a strong and significant association using commercial database controls, which was absent with NHSCR controls. CONCLUSION: There are important differences in self-reported measures of health and quality of life using controls from two alternative population sampling frames. It emphasizes the importance of methodological rigor and prior assessment in choosing sampling frames for case-control studies.