Background/Purpose: A recent hospital-based study has suggested an 8 fold increased risk of pulmonary embolism (PE) in individuals with polymyalgia rheumatica in the year following admission.  It is unknown whether a similar risk exists among individuals with giant cell arteritis (GCA).  We estimated the risk of incident PE and deep venous thrombosis (DVT) events, and associated time trend among incident cases with GCA compared to controls from the general population using physician billing and hospitalization databases that cover the entire province (~ million).

Methods: Our data included all visits to health professionals and hospital admissions covered by the comprehensive provincial medical services plan from January 1, 1990 until December 31, 2007 for all individuals > 18 years of age.  We conducted  a matched cohort study among patients meeting the following criteria: a) ≥ 40 years of age; b) new diagnosis of GCA on at least 2 visits within a two-year period between January 1996 and December 2007; and c)use of oral glucocorticoids between 1 month before and 6 months after the second GCA visit (or first if hospital or rheumatologist). Ten controls were matched by birth year, sex and calendar year of exposure from the general population for each case. A patient was considered to be a PE or DVT case when he or she had a recorded code of PE (hospitalization) or DVT (outpatient or hospitalization).  We estimated relative risks (RRs) of PE and DVT compared with a matched non-RA comparison cohort, adjusting for age, sex, comorbidities, trauma, fracture, surgery, and hospitalizations.

Results: Among 1,175 individuals with GCA (74% female, mean age of 75 years), 22 developed PE and 24 developed DVT. Compared with non-GCA individuals, the age-, sex-, and entry-time-matched RRs were 3.6 (95% CI, 2.1-5.8) for PE and 2.7 (95 % CI 1.74-4.32) for DVT (Table). These RRs were attenuated slightly after adjusting for covariates, but remained significant.  The time-specific, age-, sex-, and entry-time-matched RRs during the first year were 15.1 (95%CI, 6.6-36.2) for PE and 5.9 (2.9-11.4) for DVT.  

Table.  Relative Risk of Incident PE and DVT According to GCA Status

	GCA	Non-GCA
PE Cases, N	22	65
Incidence Rate/1000 Person-Years	5.2	1.5
Age-, Sex-, Entry time Matched RR (95% CI)	3.6 (2.1 – 5.8)	1.0
Multivariable RR (95% CI)	3.1 (1.9-5.1)	1.0
DVT
Cases, N	24	93
Incidence Rate/1000 Person-Years	5.8	2.1
Age-, Sex-, Entry time Matched RR (95% CI)	2.7 (1.7 – 4.3)	1.0
Multivariable RR (95% CI)	2.4 (1.5 –3.9)	1.0
PE or DVT
Cases, N	36	142
Incidence Rate/1000 Person-Years	8.8	3.3
Age-, Sex-, Entry time Matched RR (95% CI)	2.7 (1.8 – 3.9)	1.0
Multivariable RR (95% CI)	2.4 (1.6 – 3.5)	1

Conclusion: This large population-based study provides the first evidence for a substantially increased risk of PE and DVT in GCA and shed light on corresponding risk trends over the duration of GCA among primarily outpatients. These findings support increased monitoring of venous-thromboembolic complications and risk factors in GCA at the population level.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/the-risk-of-pulmonary-embolism-and-deep-vein-thrombosis-in-giant-cell-arteritis-a-population-based-cohort-study/