Clinical characteristics of patients with nontuberculous mycobacterial pulmonary disease (NTM-PD) in Denmark are undescribed. This study investigated clinical characteristics and diagnostic practices in patients with pulmonary NTM isolates.

Patients in Central Region Denmark from 2016 to 2021 were identified using mycobacterial reference laboratory data, and hospital records were reviewed for demographics, comorbidities, risk factors, and diagnostic details. Diagnostic guideline criteria for NTM-PD were assessed, and clinical characteristics were compared between those who met the criteria and those who did not.

Among 193 patients, M. avium complex (56 %), M. gordonae (15 %), and M. xenopi (11 %) were most common. Symptoms included cough (62 %), expectoration (51 %), dyspnea (43 %), and systemic symptoms (42 %), with 36 % experiencing symptoms for over 6 months. The median time from first hospital contact to receipt of the first sample yielding NTM was 14 days (IQR: 42). Forty-five percent (n = 87) of patients were initially seen in a fast-track pulmonary cancer referral pathway. Fifty-three percent (n = 103) met the diagnostic criteria for NTM-PD. This was associated with older age, lower BMI and FEV1, a higher comorbidity burden, longer time to diagnostic sampling, and higher bacterial loads.

In Denmark, a high percentage of patients met the NTM-PD criteria compared to other studies, which may be attributed to a high prevalence of structural lung disease and delayed disease presentation and diagnosis. Many patients were initially seen in a fast-track pulmonary cancer pathway, which could be leveraged to improve the diagnostic pathway of NTM-PD.