Outcome of shorter treatment duration in non-cavitary nodular bronchiectatic Mycobacterium avium complex lung disease

Background: The recommended treatment duration for non-cavitary nodular bronchiectatic (NC-NB) Mycobacterium avium complex (MAC) lung disease (Li)) is at least 12 months after culture conversion, but evidence supporting this is limited. This study investigated whether treatment for less than 12 months after culture conversion is acceptable in terms of recurrence rate. Methods: The study enrolled the patients diagnosed with NC-NB MAC LD between 2001 and 2014 at a tertiary referral center in South Korea who received the standard treatment for at least 9 months after cul ture conversion up to October 2018. The patients were divided into a shorter treatment group (9-11 months after culture conversion) and a standard treatment group (>= 12 months). Results: Of the 228 patients enrolled, 59 (25.9%) were treated for 9-11 months after culture conversion and 169 (74.1%) for >= 12 months. The mean treatment durations after culture conversion in the shorter and standard treatment groups were 11.1 and 13.8 months, respectively (P<0.001). During median follow-up durations after the completion of treatment of 56.5 and 55.9 months, respectively, the recurrence rates in the two groups were similar, at 39.0% (23/59) and 36.7% (62/169). There were also no significant differences between the groups in the 1-year and 3-year recurrence rates. Conclusions: Post-conversion treatment shorter than the recommended duration may be adequate in terms of recurrence rate for patients with NC-NB MAC LD who receive the standard treatment for at least 9 months after culture conversion.