Background/Purpose:

Data on the risk of pulmonary embolism (PE) and deep venous thrombosis (DVT) in patients with systemic sclerosis (SSc) is lacking. To fill this knowledge gap, we estimated the risk of newly recorded PE and DVT among incident cases of SSc compared to controls from the general population using physician billing and hospitalization databases that cover the entire population of the province of British Columbia (~ 5 million).

Patients and Methods:

Our data included all visits to health professionals and hospital admissions from Jan 1990 until Dec 2010 and all dispensed medication from Sept 1995 to Dec 2010 for all individuals ³ 18 years of age. We conducted a matched cohort analysis among patients satisfying at least one of the following criteria: a) diagnosis of SSc on at least two visits within a two-year period between Jan 1996 and Dec 2010 by a non-rheumatologist physician; b) diagnosis of SSc on at least one visit by a rheumatologist or from a hospital. To increase specificity, we excluded cases that were not confirmed by a rheumatologist if they were seen at a later point. Ten controls matched by birth year, sex, and calendar year of follow-up were selected from the general population for each case. Our outcomes were newly recorded PE and DVT events from outpatient visits, hospital, or by death certificate. For nonfatal events, we required the use of anticoagulant medications within six-months of the PE and DVT events as part of our outcome definition. We estimated relative risks (RRs) comparing SSc with age-, sex- and entry time-matched comparison cohorts, adjusting for potential cardiovascular risk factors.

Results:

Among 1,284 individuals with incident SSc (83% female, mean age of 57 yrs [SD 15.0]), 21, 17, and 35 developed PE, DVT or both, respectively (incidence rates= 4.4, 3.6, and 7.5 per 1000 person years, respectively) (Table). Compared with non-SSc individuals (N= 12,080), the age-, sex-, and entry-time-matched RRs for PE, DVT, or both were 4.2, 4.6, and 4.7 respectively (P<0.05 for all). The risks were greatest within the first year after disease onset and progressively attenuated with time for all outcomes. The RRs were also significantly larger among men. After further adjustment for baseline obesity, hormone replacement therapy, dyslipidemia, Cox-2 inhibitors, Charlson’s comorbidity index, alcoholism/liver disease, hypertension, sepsis, varicose veins, inflammatory bowel disease, trauma, fractures, surgery, glucocorticoids, and oral contraceptives, the RRs remained similar (Table).

Conclusion:

This large population-based study is the first to demonstrate an increased risk of PE and DVT in patients with SSc, especially among men and within the first year of disease diagnosis. These findings support the need of increased monitoring of VTE complications and risk factors in those with SSc.

Table: Risk of Incident PE, DVT or DVT or PE according to SSc Status