Preliminary Observations of Veterans Without HIV Who Have Mycobacterium avium Complex Pulmonary Disease

Discussion

Consistent with previous reports in the literature, veterans in our cohort were predominantly current or former smoking males with underlying COPD and bronchiectasis.^1-3,11,12 Chest CT findings varied: Most veterans presented not only with nodules and tree-in-bud opacities, but also a high frequency of fibrosis and emphysema. PFTs revealed a variety of obstruction and restrictive patterns, and most veterans had a reduced DLCO, though it is unclear whether this is reflective of underlying emphysema, fibrosis, or an alternative cardiopulmonary disease.^13,14

While underlying structural lung disease may have been a risk factor for MAC-PD in this cohort, the contribution of environmental and domiciliary factors in metropolitan Chicago neighborhoods is unknown. JBVAMC serves an underresourced population who live in the west and south Chicago neighborhoods. Household factors, ambient and indoor air pollution, and potential contamination of the water supply and surface soil may contribute to the prevalence of MAC-PD in this group.^15-19 Further studies are warranted to characterize MAC-PD and its treatment in veterans without HIV who reside in underresourced urban communities in the US.

Recent ATS, European Society of Clinical Microbiology and Infectious Diseases, and IDSA guidelines recommend combination antimycobacterial therapy for patients who meet clinical, radiographic, and microbiologic criteria for the diagnosis of MAC-PD.¹⁰ Patients who meet these diagnostic criteria, particularly patients with smear positivity or fibrocavitary disease, should be treated because of risk of unfavorable outcomes.^15,20-22 However, we found that the initiation of guideline-recommended antimycobacterial therapy in veterans without HIV with MAC-PD were inconsistent among HCPs. The reasons underlying this phenomenon were not apparent beyond cited reasons for treatment initiation or deference. Despite this inconsistency, there was no clear difference in age, BMI, symptom burden, radiographic abnormality, or all-cause mortality between treatment groups. Existing studies support slow but substantial progression of untreated MAC-PD, and while treatment prevents deterioration of the disease, it does not prevent progression of bronchiectasis.⁶ The natural history of MAC-PD in this veteran cohort has yet to be fully elucidated. Furthermore, the 50% treatment dropout rate was higher than previously reported rates (11-33%).⁵ However, the small number of veterans in this study precludes meaningful comparison with similar reports in the literature.

We did note a relatively high all-cause mortality in this cohort (n = 6, 32%); however, this rate is comparable to the all-cause mortality rate of 27% observed in a 2018 meta-analysis of 9035 patients with MAC-PD.²³ Although there was no major difference in those deceased and those alive at the time of data collection in our study, previously described predictors of mortality included male sex, advanced age, presence of fibrocavitary disease, decreased FVC, and presence of comorbidities.^8,23 Larger prospective studies evaluating veterans with MAC-PD are needed to further evaluate contributors to mortality in veterans with MAC-PD.

Limitations

The limitations of this small, single-center, retrospective study prevent a robust, generalizable comparison between groups. Further studies are warranted to characterize MAC-PD and its treatment in veterans without HIV who reside in underresourced urban communities in the US.^24-26

Conclusions

These data suggest that clinical, imaging, and treatment attributes of MAC-PD in veterans without HIV who reside in metropolitan Chicago are heterogeneous and are associated with a relatively high mortality rate. Although there was no difference in the attributes or outcomes of veterans who did and did not initiate treatment despite current recommendations, further studies are needed to better explore these relationships.