Abstract
Mycobacterium abscessus group lung infection is characterized by low cure rates. Improvement in quality of life may be a reasonable treatment goal.
The objective of this study was to evaluate change in quality of life in response to therapy, predictors of improvement in quality of life, and association of quality of life with traditional outcome measures.
Forty-seven patients were treated for Mycobacterium abscessus group lung infection (including one with Mycobacterium chelonae) and were followed prospectively for 2 years between December 2009 and May 2012. St. George's Respiratory Questionnaire (SGRQ) was administered, chest computed tomography (CT) imaging was carried out, and culture data were collected at multiple time points. Predictors of improvement in the SGRQ total score greater than or equal to a minimal clinically important difference (MCID) at 12 months were evaluated.
Patients were 85% female and 94% white, with a mean age of 65 years. Nine (20%) had a genetic diagnosis of cystic fibrosis (none F508del homozygous). Coinfection with Mycobacterium avium complex occurred in 28% and Pseudomonas in 26%. Chest CT imaging universally indicated bronchiectasis and nodules; 51% had lung cavities. Treatment included a mean of 17 months of antibiotics, and lung resection in 34%. Seventeen patients with M. avium complex (36%) and one with Mycobacterium kansasii were treated for coinfection. The mean SGRQ total score (SD) at baseline was 35 (20). At all follow-up time points, the mean SGRQ total score (SD) was significantly lower (better) than at baseline: 27 (17) at 3 months, P < 0.01; 27 (19) at 6 months, P < 0.01; 27 (20) at 12 months, P < 0.01; and 30 (22) at 24 months, P = 0.02. At 12 and 24 months, respectively, 60% and 56% had improvement greater than or equal to the MCID in SGRQ total score. Improvement greater than or equal to the MCID at 12 months was positively associated with a history of respiratory exacerbation, isolate susceptible to imipenem-cilastatin, and lung resection surgery, and negatively associated with nodules >4 mm in diameter on chest CT imaging, but these associations were not statistically significant in multivariable analysis. At 24 months, 16 patients (48%) with complete data were culture negative for 1 year and had discontinued M. abscessus group treatment.
Quality of life was a sensitive indicator of treatment response and has the potential to be a useful parameter to guide treatment.