Decreased incremental shuttle walk test distance characterized by fibrocavitary lesions in non-tuberculous mycobacterial pulmonary disease

ABSTRACT

Background

Patients with non-tuberculous mycobacterial pulmonary disease (NTM-PD) have impaired exercise capacity, but the underlying factors are unknown. We investigated the characteristics of patients with NTM-PD and impaired exercise capacity.

Methods

In total, 149 patients with NTM-PD participated in this study. Patients completed the incremental shuttle walk test (ISWT) to assess exercise capacity. Peripheral muscle strength and pulmonary function were also assessed. Radiological findings were classified into three phenotypes: non-cavitary nodular bronchiectatic (NC-NB) form, cavitary nodular bronchiectatic form, and fibrocavitary (FC) form.

Results

The median ISWT distance (ISWD) and %ISWD were 450 meters and 88%. Participants were classified into three groups according to %ISWD, with %ISWD <60% as the severely decreased group, 60%-80% as the moderately decreased group, and >80% as the normal or mildly decreased group. In a comparison of %ISWD among phenotypes, FC form had significantly lower %ISWD than those with NC-NB form. In the severely decreased group, peripheral muscle strength and pulmonary function were significantly lower than the other two groups. From a radiological standpoint, significantly more patients had FC form in the group with severely decreased %ISWD.

Conclusions

Decreased ISWD is characterized by a deterioration in physical function and the presence of FC lesions in NTM-PD.

KEYWORDS:

• Non-tuberculous mycobacteria
• mycobacterium avium complex
• incremental shuttle walk test

Acknowledgments

We thank Yuki Toyoda (Respiratory Care and Rehabilitation Center, Fukujuji Hospital, Japan Anti-Tuberculosis Association, Tokyo, Japan) for collecting data. We thank Analisa Avila, MPH, ELS, of Edanz (https://jp.edanz.com/ac) for editing a draft of this manuscript.

Declaration of interest

The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties.

Author contributions

Study conception and design: K. Ono, H. Kimura and H. Senjyu.

Data collection: K. Ono, M. Tabusadani, K. Yamane, S. Takao, K. Mori, Y. Matsumura, Y. Kuroyama, K. Kawahara, S. Omatsu, K. Furuuchi, K. Fujiwara, K. Morimoto.

Data analysis and interpretation: K. Ono, H. Kimura and H. Senjyu.

Manuscript preparation: K. Ono, H. Kimura and H. Senjyu.

Manuscript final review: All authors

Reviewer disclosures

Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

This paper was not funded.