The study compared 125 newly diagnosed NTM-PD patients with 1250 control patients matched by age, gender and Charlson Comorbidity Index over a period of 39 months. During this time period the all-cause mortality rate for those diagnosed with NTM-PD was 22.4%, almost four times higher than the matched control group (6%) (P<0.001). In the same observation period, the all-cause mortality rate in COPD patients who had NTM-PD was 41.5% (27/65 patients) but was only 15.9% (62/390) in COPD patients without NTM-PD (P<0.001).
NTM-PD is a rare but emerging global health concern, with important public health implications. The infection is caused by ubiquitous mycobacteria found in the soil and water. Over 150 species of NTM have been identified and mycobacterium avium complex (MAC) has been reported to be the most common causative agent in NTM-PD worldwide. Diseases caused by NTMs represent a growing diagnostic and clinical challenge. In recent decades, the incidence, prevalence, hospitalisation rate, and mortality rate of NTM-PD have increased worldwide.
NTMs represent a risk of infection for susceptible individuals – these are often patients with a predisposing chronic pulmonary disease, such as COPD or bronchiectasis. For these patients, the symptoms of the underlying disease overlap with the non-specific symptoms of NTM-PD, often leading to correct diagnosis often only being made at a late stage. From a therapeutic perspective, NTM-PD is more challenging than uncomplicated pulmonary tuberculosis: treatment is lengthy, toxic and often fails. Initial treatment has the highest chance of success.
The mean direct expenditure for an NTM-PD patient was €39,559.60 over 39 months, also almost four times higher than the matched control group (€10,006.71). Hospitalisations were three times higher for NTM-PD patients and accounted for the majority of expenditure (63%), with drug costs being the second biggest costs. Also notable was the discrepancy across individual treatments—only 54% of patients received antibiotics on diagnosis, 26% never received antibiotics at all, and 29 different drug combinations were observed across all treatments.
Clarithromycin combined with ethambutol was the most frequently prescribed treatment option in 24/93, or 25.8%, of the treated patients, followed by standard treatment clarithromycin plus rifampicin plus ethambutol or rifabutin plus ethambutol in 18/93 patients (19.4%) and 14/93 patients (15.1%), respectively.
“Although NTM-PD is considered rare, these findings highlight that the burden of the disease is high,” commented Dr Michael Loebinger of the Royal Brompton Hospital, London and one of the study’s authors. “Treatment can be hard to tolerate and may be unsuccessful, making treatment decisions complex. To help with this challenge, the British Thoracic Society will be releasing new guidelines this year.”