Trends of non-tuberculous mycobacterial disease in a low-tuberculosis prevalence setting.

Background: Limited data are available regarding factors associated with initiation of treatment and treatment outcomes after diagnosis of non-tuberculous mycobacteria (NTM) pulmonary infection and disease. Objective: To investigate trends of NTM pulmonary infections, patient characteristics and factors associated with initiation of treatment and treatment outcomes in patients with NTM pulmonary infection and disease. Methods: We evaluated 154 patients with NTM pulmonary infection, identified by having at least one record coded with ICD-10 A31.0 at Haukeland University Hospital in Bergen, Norway, from 2000 to 2021. A univariate and multivariate binary logistic regression was carried out to find the odds of factors associated with the initiation of treatment and treatment outcomes. Results: 70% of the patients were older than 65 years. 49 % of patients had pulmonary comorbidity and the three most common symptoms were cough, dyspnoea, and weight loss. The most frequently observed mycobacterial species was M. avium complex (MAC), followed by M. malmoense, and M. abscessus. There was a decreasing trend in NTM pulmonary infection and NTM pulmonary disease from the year 2000 to 2014, while an increase was observedfrom 2015 to 2019. A total of 72 (47%) patients received antibiotic treatment. Patients with high symptom scores, those below the age of 65, and those with MAC infection had more than three times the odds of receiving antibiotic treatment (P = 0.006, P = 0.006, and P = .005 respectively). Of 72 patients who received treatment, 53 (74%) had a favourable response and culture conversion. 17 (32%) of them had a relapse. Out of 82 patients who did not receive treatment, 45 (55%) had spontaneous culture conversion. 8 (18%) of them had a relapse. No factor was identified to be significantly associated with a favourable treatment response including the time taken to start treatment or presence of pulmonary cavities. Conclusion: Favourable response to treatment was seen in 74% patients whereas spontaneous culture conversion was seen in 55% of non-treated patients. Factors associated with favourable treatment response were not found. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study did not receive any funding ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Ethics committee of the Regional Committee for Medical Ethics Western Norway gave ethical approval for this work I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors