Risk factors for recurrent Mycobacterium ulcerans disease after exclusive surgical treatment in an Australian cohort.

OBJECTIVE

To describe risk factors for recurrence after exclusive surgical treatment of Mycobacterium ulcerans infection.

DESIGN, SETTING AND PARTICIPANTS: Prospective observational cohort study of all M. ulcerans cases managed with surgery alone at Barwon Health, a tertiary referral hospital, from 1 January 1998 to 31 December 2011. A random-effects Poisson regression model was used to assess rates and associations of treatment failure.

MAIN OUTCOME MEASURES

Rates of treatment failure and rate ratios (RRs) for factors associated with treatment failure.

RESULTS

Of 192 patients with M. ulcerans infection, 50 (26%) had exclusive surgical treatment. Median age was 65.0 2013s (interquartile range [IQR], 45.5-77.7 2013s), and median duration of symptoms was 46 days (IQR, 26-90 days). There were 20 recurrences in 16 patients. For first lesions, the recurrence incidence rate was 41.8 (95% CI, 25.6-68.2) per 100 person-2013s, and median time to recurrence was 50 days (IQR, 30-171 days). Recurrence occurred ≤ 3 cm from the original lesion in 13 cases, and > 3 cm in nine. On univariable analysis, age ≥ 60 2013s (RR 13.84; 95% CI, 2.21-86.68; P < 0.01), distal lesions (RR, 20.43; 95% CI, 1.97-212.22; P < 0.01), positive histological margins (RR, 21.02; 95% CI, 5.51-80.26; P < 0.001), immunosuppression (RR, 17.97; 95% CI, 4.17-77.47; P < 0.01) and duration of symptoms > 75 days (RR, 10.13; 95% CI, 1.76-58.23; P = 0.02) were associated with treatment failure. On multivariable analysis, positive margins (RR, 7.72; 95% CI, 2.71-22.01; P < 0.001) and immunosuppression (RR, 6.45; 95% CI, 2.42-17.20; P = 0.01) remained associated with treatment failure.

CONCLUSIONS

Recurrence rates after exclusive surgical treatment of M. ulcerans disease in an Australian cohort are high, with increased rates associated with immunosuppression or positive histological margins.