Age, Sex, and Bodyweight
Over an average of 8.2 years’ follow-up, the adjusted hazard ratios (aHRs) comparing VTE risk in women and men with and without RA were a respective 1.62 and 1.52. The corresponding aHRs for VTE according to different age groups were 2.13 for age 18-49 years, 1.57 for age 50-69 years, and 1.34 for age 70 years and older.
“The highest excess risk was in the youngest age group,” Dr. Galloway pointed out, “but all age groups showing a significant increased risk of venous thromboembolism.”
Similar findings were seen across different BMI categories, with the highest risk occurring in those in the lowest BMI group. The aHRs were 1.66, 1.60, and 1.41 for the BMI categories of less than 25 kg/m2, 25-30 kg/m2, and more than 30 kg/m2, respectively.
Duration of RA
As for disease duration, nearly two thirds (63.9%) of the 23,410 adults with RA included in this analysis were included at or within 2 years of a diagnosis of RA, 7.8% within 2-5 years of diagnosis, 9.8% within 5-10 years of diagnosis, and 18.5% at 10 or more years after diagnosis.
The aHR for an increased relative risk for VTE in people with RA vs the control group ranged from 1.49 for 0-2 years of diagnosis up to 1.63 for more than 10 years since diagnosis.
“We could see no evidence that the VTE excess risk in rheumatoid arthritis was with a specific time since diagnosis,” Dr. Galloway said in the interview. “It appears that the risk is increased in people with established RA, whether you’ve had the disease for 2 years or 10 years.”
Similar findings were also seen when they looked at aHRs for pulmonary embolism (1.46-2.02) and deep vein thrombosis (1.43-1.89) separately.
Oral Contraceptives and HRT
Data on the use of estrogen-based oral contraceptives or HRT were detailed in a virtual poster presentation. In this analysis, there were 16,664 women with and 65,448 without RA, and the average follow-up was 8.3 years.
“The number of people available for this analysis was small, and bigger studies are needed,” Dr. Galloway said in the interview. Indeed, in the RA group, just 3.3% had used an estrogen-based oral contraceptive and 4.5% had used HRT compared with 3.9% and 3.8% in the control group, respectively.
The overall VTE risk was 52% higher in women with RA than in those without RA.
Risk for VTE was higher among women with RA regardless of the use of estrogen-based oral contraceptives or not (aHRs, 1.43 and 1.52, respectively) and regardless of the use of HRT or not (aHRs, 2.32 and 1.51).
Assess and Monitor
Together these data increase understanding of how age, gender, obesity, duration of disease, and estrogen-based contraception and HRT may make a difference to someone’s VTE risk.
“In all people with RA, we observe an increased risk of venous thromboembolism, and that is both relevant in a contemporary era when we think about prescribing and the different risks of drugs we use for therapeutic strategies,” Dr. Galloway said.
The overall take-home message, he said, is that VTE risk should be considered in everyone with RA and assessed and monitored accordingly. This includes those who may have traditionally been thought of as having a lower risk than others, such as men vs women, younger vs older individuals, and those who may have had RA for a few years.
The research was funded by Pfizer. Dr. Galloway reported receiving honoraria from Pfizer, AbbVie, Biovitrum, Bristol Myers Squibb, Celgene, Chugai, Galapagos, Janssen, Lilly, Novartis, Roche, Sanofi, Sobi, and UCB. Two coauthors of the work were employees of Pfizer. Dr. Bukhari had no conflicts of interest and was not involved in the research.
A version of this article appeared on Medscape.com.