Lower Frequency of Comorbidities Prior to Onset of Giant Cell Arteritis: A Population-Based Study

Phase-Specific Healthcare Costs Associated With Giant Cell Arteritis in Ontario, Canada

OBJECTIVE

To estimate the additional healthcare system costs associated with giant cell arteritis (GCA) in the 1-year prediagnosis and postdiagnosis periods and over long-term follow-up compared to individuals with similar demographics and comorbidities without GCA.

METHODS

We performed a population-based study using health administrative data. Newly diagnosed cases of GCA (between 2002 and 2017 and aged ≥ 66 years) were identified using a validated algorithm and matched 1:6 to comparators using propensity scores. Follow-up data were accrued until death, outmigration, or March 31, 2020. The costs associated with care were determined across 3 phases: the year before the diagnosis of GCA, the year after, and ongoing costs thereafter in 2021 Canadian dollars (CAD).

RESULTS

The cohort consisted of 6730 cases of GCA and 40,380 matched non-GCA comparators. The average age was 77 (IQR 72-82) years and 68.2% were female. A diagnosis of GCA was associated with an increased cost of CAD $6619.4 (95% CI 5964.9-7274.0) per patient during the 1-year prediagnostic period, $12,150.3 (95% CI 11,233.1-13,067.6) per patient in the 1-year postdiagnostic phase, and $20,886.2 (95% CI 17,195.2-24,577.2) per patient during ongoing care for year 3 onward. Increased costs were driven by inpatient hospitalizations, physician services, hospital outpatient clinic services, and emergency department visits.

CONCLUSION

A diagnosis of GCA was associated with increased healthcare costs during all 3 phases of care. Given the substantial economic burden, strategies to reduce the healthcare utilization and costs associated with GCA are warranted.

Reappraisal of large artery involvement in giant cell arteritis: a population-based cohort over 70 years

OBJECTIVE

To evaluate the incidence and outcomes of large artery (LA) involvement among patients with giant cell arteritis (GCA) and to compare LA involvement to non-GCA patients.

METHODS

The study included Olmsted County, Minnesota, USA residents with incident GCA between 1950 and 2016 with follow-up through 31 December 2020, death or migration. A population-based age-matched/sex-matched comparator cohort without GCA was assembled. LA involvement included aortic aneurysm, dissection, stenosis in the aorta or its main branches diagnosed within 1 year prior to GCA or anytime afterwards. Cumulative incidence of LA involvement was estimated; Cox models were used.

RESULTS

The GCA cohort included 289 patients (77% females, 81% temporal artery biopsy positive), 106 with LA involvement.Reported cumulative incidences of LA involvement in GCA at 15 years were 14.8%, 30.2% and 49.2% for 1950-1974, 1975-1999 and 2000-2016, respectively (HR 3.48, 95% CI 1.67 to 7.27 for 2000-2016 vs 1950-1974).GCA patients had higher risk for LA involvement compared with non-GCA (HR 3.22, 95% CI 1.83 to 5.68 adjusted for age, sex, comorbidities). Thoracic aortic aneurysms were increased in GCA versus non GCA (HR 13.46, 95% CI 1.78 to 101.98) but not abdominal (HR 1.08, 95% CI 0.33 to 3.55).All-cause mortality in GCA patients improved over time (HR 0.62, 95% CI 0.41 to 0.93 in 2000-2016 vs 1950-1974) but remained significantly elevated in those with LA involvement (HR 1.89, 95% CI 1.39 to 2.56).

CONCLUSIONS

LA involvement in GCA has increased over time. Patients with GCA have higher incidences of LA involvement compared with non-GCA including thoracic but not abdominal aneurysms. Mortality is increased in patients with GCA and LA involvement highlighting the need for continued surveillance.

Apolipoproteins and the risk of giant cell arteritis-a nested case-control study

BACKGROUND

The etiology of giant cell arteritis (GCA) and its predictors are incompletely understood. Previous studies have indicated reduced risk of future development of GCA in individuals with obesity and/or diabetes mellitus. There is limited information on blood lipids before the onset of GCA. The objective of the study was to investigate the relation between apolipoprotein levels and future diagnosis of GCA in a nested case-control analysis.

METHODS

Individuals who developed GCA after inclusion in a population-based health survey (the Malmö Diet Cancer Study; N = 30,447) were identified by linking the health survey database to the local patient administrative register and the national patient register. A structured review of medical records was performed. Four controls for every validated case, matched for sex, year of birth, and year of screening, were selected from the database. Anthropometric measures, self-reported physical activity, based on a comprehensive, validated questionnaire, and non-fasting blood samples had been obtained at health survey screening. Concentrations of apolipoprotein A-I (ApoA-I) and apolipoprotein B (ApoB) in stored serum were measured using an immunonephelometric assay. Potential predictors of GCA were examined in conditional logistic regression models.

RESULTS

There were 100 cases with a confirmed clinical diagnosis of GCA (81% female; mean age at diagnosis 73.6 years). The median time from screening to diagnosis was 12 years (range 0.3-19.1). The cases had significantly higher ApoA-I at baseline screening compared to controls (mean 168.7 vs 160.9 mg/dL, odds ratio [OR] 1.57 per standard deviation (SD); 95% confidence interval [CI] 1.18-2.10) (SD 25.5 mg/dL). ApoB levels were similar between cases and controls (mean 109.3 vs 110.4 mg/dL, OR 0.99 per SD; 95% CI 0.74-1.32) (SD 27.1 mg/dL). The ApoB/ApoA1 ratio tended to be lower in cases than in controls, but the difference did not reach significance. The association between ApoA-I and GCA development remained significant in analysis adjusted for body mass index and physical activity (OR 1.48 per SD; 95% CI 1.09-1.99).

CONCLUSION

Subsequent development of GCA was associated with significantly higher levels of ApoA-I. These findings suggest that a metabolic profile associated with lower risk of cardiovascular disease may predispose to GCA.

Updating and Validating the Rheumatic Disease Comorbidity Index to Incorporate ICD-10-CM Diagnostic Codes

OBJECTIVE

To update and validate the Rheumatic Disease Comorbidity Index (RDCI) utilizing International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) codes.

METHODS

We defined ICD-9-CM (n = 1,068) and ICD-10-CM (n = 1,425) era cohorts (n = 862 in both) spanning the ICD-9-CM to ICD-10-CM transition in a multicenter, prospective rheumatoid arthritis registry. Information regarding comorbidities was collected from linked administrative data over 2-year assessment periods. An ICD-10-CM code list was generated from crosswalks and clinical expertise. ICD-9- and ICD-10-derived RDCI scores were compared using intraclass correlation coefficients (ICC). The predictive ability of the RDCI for functional status and death during follow-up was assessed using multivariable regression models and goodness-of-fit statistics (Akaike's information criterion [AIC] and quasi information criterion [QIC]) in both cohorts.

RESULTS

Mean ± SD RDCI scores were 2.93 ± 1.72 in the ICD-9-CM cohort and 2.92 ± 1.74 in the ICD-10-CM cohort. RDCI scores had substantial agreement in individuals who were in both cohorts (ICC 0.71 [95% confidence interval 0.68-0.74]). Prevalence of comorbidities was similar between cohorts with absolute differences <6%. Higher RDCI scores were associated with a greater risk of death and poorer functional status during follow-up in both cohorts. Similarly, in both cohorts, models including the RDCI score had the lowest QIC (functional status) and AIC (death) values, indicating better model performance.

CONCLUSION

The newly proposed ICD-10-CM codes for the RDCI-generated comparable RDCI scores to those derived from ICD-9-CM codes and are highly predictive of functional status and death. The proposed ICD-10-CM codes for the RDCI can be used in rheumatic disease outcomes research spanning the ICD-10-CM era.

Can active sun exposure decrease the risk of giant cell arteritis and polymyalgia rheumatica in women?

Objectives

To study if active sun exposure among women affects the risk of developing GCA or PMR in a prospective cohort study with restricted latitudinal variability.

Methods

We linked the response to questions relating to sun exposure from the Melanoma Inquiry in Southern Sweden (MISS) prospective cohort study in women to the risk of developing GCA or PMR. Healthcare data were gathered from the Skåne Healthcare Register (SHR), covering all public healthcare consultations. The direct effect of active sun exposure on the risk of developing GCA or PMR was assessed using Cox proportional hazards models adjusted for covariates based on a directed acyclic graph.

Results

A total of 14 574 women were included in the study; 601 women were diagnosed with GCA or PMR (144 and 457, respectively) during the follow-up time. Women with moderate or high sun exposure were not less likely to develop GCA or PMR compared with women that indicated they avoided sun exposure [hazard ratio (HR) 1.2 (CI 0.9, 1.6) and 1.3 (0.9, 1.9), respectively] when adjusted for diabetes, hyperlipidaemia, hypertension, smoking, obesity and stratified by age. Similar patterns were observed when studying only GCA [HR 1.2 (CI 0.7, 2.3) and 1.3 (0.7, 2.6)] and only PMR [HR 1.3 (CI 0.9, 1.8) and 1.4 (0.9, 2.0)].

Conclusion

Active sun exposure did not affect the risk of developing GCA or PMR in women in a cohort with restricted latitudinal variability.