Service discharges among US Army personnel with selected musculoskeletal and skin conditions: a retrospective cohort study

OBJECTIVES

To determine the probability of discharge from military service among soldiers following an incident diagnosis of ankylosing spondylitis (AS), rheumatoid arthritis (RA), psoriasis or systemic lupus erythematous.

METHODS

All soldiers on active duty in the US Army between January 2014 and June 2017 were included in a retrospective cohort analysis. Termination from service was ascertained using personnel records. Diagnostic codes were used to identify incident cases of the four musculoskeletal and skin diseases and, for comparison, diabetes mellitus (DM). Time to discharge was modelled using sex stratified multivariate survival analysis.

RESULTS

The analysis included 657 417 individuals with a total of 1.2 million person-years of observation. An elevated risk of discharge was observed in association with each of the five chronic conditions studied. The increase in adjusted risk of discharge was highest among soldiers with AS (men, HR=2.5, 95% CI 2.1 to 3.0; women, HR=2.1, 95% CI 1.4 to 3.2) and with DM (men, HR=2.4, 95% CI 2.2 to 2.7; women, HR=2.2, 95% CI 1.8 to 2.5), followed by those with RA (men, HR=1.8, 95% CI 1.5 to 2.2; women, HR=1.8, 95% CI 1.4 to 2.4).

CONCLUSIONS

Military discharges are consequential for the service and the service member. The doubling in risk of discharge for those with AS or RA was comparable to that for personnel with DM. Conditions that affect the spine and peripheral joints may often be incompatible with military readiness. Nevertheless, a substantial fraction of service members with these diagnoses continued in service.

Circulating mature granzyme B+ T cells distinguish Crohn's disease-associated axial spondyloarthritis from axial spondyloarthritis and Crohn's disease

BACKGROUND

Axial spondyloarthritis (axSpA) has strong connections with intestinal inflammation as occurs in Crohn's disease (CD). However, the immunologic mechanisms that distinguish axSpA, CD, and those with features of both diseases (CD-axSpA) are unknown. This study aimed to address this question by initial unbiased single cell RNA-sequencing (scRNAseq) on a pilot cohort followed by validating findings using flow cytometry and ELISA in a larger cohort.

METHODS

Two individuals each with CD, axSpA, CD-axSpA, and healthy controls (HC) were recruited for a pilot discovery scRNAseq cohort, and the validation cohort consisted of 18 axSpA, 24 CD, 13 CD-axSpA, and 17 HC that was evaluated by flow cytometry on PBMCs and ELISAs for plasma cytokines.

RESULTS

Uniquely, PBMCs from subjects with CD-axSpA demonstrated a significant increase in granzyme B+ T cells of both CD4+ and CD8+ lineages by both scRNAseq and flow cytometry. T cell maturation was also greater in those with CD-axSpA, particularly the CD4+ granzyme B+ population. Pathway analysis suggested increased interferon response genes in all immune cell populations within CD-axSpA. Although IFN-γ was elevated in the plasma of a subset of subjects with CD-axSpA, IL-6 was also significantly elevated.

CONCLUSIONS

Our findings support the presence of a chronic interferonopathy in subjects with CD-axSpA characterized by interferon signaling by pathway analysis and an expansion of mature, cytotoxic T cells. These data indicate fundamental immunological differences between CD-axSpA and both of the putative "parent" conditions, suggesting that it is a distinct disease with unique natural history and treatment needs.