Epidemiology of Nontuberculous Mycobacterial Lung Disease among Cystic Fibrosis Patients Residing in Hawaii, USA

Abstract

BackgroundPersons with cystic fibrosis (CF) are at increased risk for nontuberculous mycobacteria (NTM) lung infections, with a national annual prevalence of 13%. However, for CF patients in Hawaii, estimates are as high as 50%. Active duty military who have dependents with CF may be transferred to Hawaii as part of their service, potentially placing their dependent at increased risk for NTM. To better describe the epidemiology of NTM in a high-risk environment, we report prevalence and risk factors for CF patients living in Hawaii and seeking care at Tripler Army Medical Center (TAMC), the only CF center in Hawaii.MethodsData were extracted on CF patients treated at TAMC from 2010 to 2014, including sex, age, time residing in Hawaii, and culture results. NTM cases (≥ 1 positive culture) and non-cases (no positive cultures) were identified and prevalence estimated. Log-binomial regression was used to estimate adjusted relative risks (aRR) and 95% confidence intervals (CI) for risk factors.ResultsOf 43 CF patients, 17 (40%) had NTM isolated at least once; 11 (26%) had ≥2 positives. Annual prevalence averaged 30%. Overall, 13 (76%) cases had Mycobacterium abscessus, 5 (29%) M. avium complex (MAC), and 6 (35%) other rapid growers isolated; 9 (53%) had multiple species isolated. Mean time to first positive culture was 1.6 yrs (range: 0–7.1); only 2(11%) cases were positive at first culture. NTM cases were more frequently female (59%; P = 0.02) and older than non-cases (14.4 vs. 11.9 yrs; P < 0.0001). Among CF patients living in Hawaii for >6 years, 80% had NTM compared with only 19% of those in Hawaii for <3 years (P < 0.05) (Figure 1). After adjusting for sex and age, each additional year in Hawaii increased the risk for NTM by over two-fold (aRR=2.5, 95% CI=1.2–5.6; P = 0.02), especially for M. abscessusand other rapid growers (aRR=2.4, 95% CI=1.0–5.8; P = 0.04).ConclusionPrevalence of NTM in CF patients in Hawaii is two-fold greater than the national average, with each additional year of residence more than doubling the risk of infection. Further, nearly 80% of patients had M. abscessus, which is harder to treat and is associated with more severe clinical outcomes. Persons affected by CF should be aware of the increased risk of NTM associated with residence in Hawaii.This work was supported in part by the DIR, NIAID, NIH and by TAMC.Disclosures All authors: No reported disclosures.