Increased Risk of Systemic Lupus Erythematosus in PTSD Patients

Siobhan M. Case, MD, MHS

A multicenter study from Massachusetts found that patients with prior post traumatic stress disorder (PTSD) were twice as likely to develop a subsequent diagnosis of systemic lupus erythematosus (SLE). The cases were identified in patients enrolled in the Medicaid program.

Systemic lupus erythematosus has been linked to clinical morbidity, kidney failure, heart disease, and premature death, and the prevalence of general of lupus and lupus nephritis are much higher in women and minority groups.

A prominent risk factor in the development of the chronic autoimmune disease was PTSD, and several traumatic events such as combat and sexual assault had been linked to changes in the immune system in prior studies.

With the recent study, Siobhan M. Case, MD, MHS, and colleagues examined the role PTSD had in the development of SLE in a diverse group of Medicaid patients.

The Study

The case-controlled study included 10,942 patients with cases of incident SLE, 94% of whom were female and came from diverse racial and ethnic backgrounds.

The investigators utilized the Medicaid Analytic eXtract (MAX) database to collect data on patients 19-65 years old. Participants were culled from the 29 most populated states in the US between January 1, 2007-December 31, 2010.

Incidents of SLE in patients were defined by having >3 ICD-9 codes from hospital discharge diagnoses or physician visit claims occurring at least 30 days apart. A control group was matched 1:10 to cases for age at index date, sex, and race/ethnicity.

Exposure for PTSD was based on an algorithm approved in a Veteran administration population with a positive predictive value (PPV) of 82%. Exposure was defined as having >2 ICD-9 codes for PTSD on different dates throughout 4 months.

Case and fellow investigators also administered a 20-item self-administered survey in the form of a PTSD Checklist for DSM-5 (PCL-5) to 67 civilian subjects who were also predominantly female (87%) with a mean age of 52 years.

In addition to sex, race and ethnicity, the team also assessed variables associated with socioeconomic status (SES) including obesity, tobacco use, and oral contraceptive use.

Finally, they performed 2 sensitivity analyses and 1 stratified analysis.

The first sensitivity analysis excluded SLE cases with less than 24 months of enrollment without a code for SLE prior to the index date to increase the likelihood. The second sensitivity analysis excluded all patients with less than 6 months between the first code for PTSD and the first code for SLE or matched index date to increase the likelihood that PTSD occurred before the index date.

The stratified analysis compared the association of PTSD and SLE in individuals living in zip codes in the bottom and top half median household income brackets.

Results

The investigators found that in the first sensitivity analysis, the prevalence of PTSD was 15.74 (95% CI 12.71-19.49) among cases of SLE as opposed to 9.97 (95% CI 9.09-10.93). Also, the incidence of PTSD among cases of SLE was 7.95 (95% CI 5.88-10.76), compared to 6.51 (95% CI 5.81-7.30) among controls.

The odds ratio for SLE in conditional logistic regression presented in the second sensitivity analysis was 2.11 (95% CI 1.74-2.57).

Researchers found no significant multiplicative interaction between PTSD and continuous area-level SES. However, they admitted 1 limitation to their study was a lack of a broader racially, ethnically, and sociodemographic-diverse study population.

Overall, while Case and her colleagues called for more research to be conducted regarding the relationship between PTSD and SLE, they remained confident in their findings of a doubling of odds of SLE associated with a prior diagnosis of PTSD.

They went on to urge researchers to seek out possible interventions that could mitigate the risk of developing autoimmune disease once a patient is diagnosed with PTSD, as well as determine which groups in the US population are truly the most vulnerable.

“Likewise, characterizing the ongoing interplay between PTSD symptoms and the later disease course of SLE could illuminate common pathways to target for treatment of both conditions,” the team said.

The study, “Post-Traumatic Stress Disorder (PTSD) and Risk of Systemic Lupus Erythematosus (SLE) among Medicaid Recipients,” was published online in Arthritis Care & Research.