Risk factors affecting treatment outcomes for pulmonary tuberculosis in Finland 2007-2014: a national cohort study

BACKGROUND

Major transition in tuberculosis (TB) epidemiology is taking place in many European countries including Finland. Monitoring treatment outcome of TB cases is important for identifying gaps in the national TB control program, in order to strengthen the system. The aim of the study was to identify potential risk factors for non-successful TB treatment outcomes, with a particular focus on the impact of comorbidities. We also evaluated the treatment outcome monitoring system.

METHODS

All notified microbiologically confirmed pulmonary TB cases in Finland in 2007-2014 were included, except multi-drug resistant (MDR) cases. Nationwide register data were retrieved from: Infectious Diseases Register, Population Register, Cause of Death Register and Hospital Discharge Register. Non-successful outcomes were divided into three groups: death, unsatisfactory outcomes and non-defined outcomes. Logistic regression analyses were used to identify risk factors for non-successful outcomes.

RESULTS

Treatment outcomes were notified for 98.6% of study cases (n = 1396/1416). Treatment success rate was 75%. The main reason for non-successful outcome was death (16%), whereas outcomes failed and lost to follow-up were rare (1% together). In a multivariable model, risk factors for death as outcome were increasing age, male gender and Charlson comorbidity index ≥1, for unsatisfactory outcomes non-MDR drug resistance and TB registered in the first study period, and for non-defined outcomes non-MDR drug resistance. Among 50 cases with unsatisfactory outcomes, we observed false outcome allocations in eight (16%), and > 2% of the cases transferred to another country or disappeared before or during treatment.

CONCLUSIONS

With a high proportion of older population among tuberculosis cases, death is a common treatment outcome in Finland. Comorbidity is an important factor to be incorporated when interpreting and comparing outcome rates. There was a considerable inconsistency in outcome allocation in the monitoring system, which implies that there is need to review the guidelines and provide further training for outcome assessment.

Recurrent tuberculosis in Finland 1995-2013: a clinical and epidemiological cohort study

Background

We investigated the epidemiology and prevalence of potential risk factors of tuberculosis (TB) recurrence in a population-based registry cohort of 8084 TB cases between 1995 and 2013.

Methods

An episode of recurrent TB was defined as a case re-registered in the National Infectious Disease Register at least 360 days from the date of the initial registration. A regression model was used to estimate risk factors for recurrence in the national cohort. To describe the presence of known risk factors for recurrence, patient records of the recurrent cases were reviewed for TB diagnosis confirmation, potential factors affecting the risk of recurrence, the treatment regimens given and the outcomes of the TB episodes preceding the recurrence.

Results

TB registry data included 84 patients, for whom more than 1 TB episode had been registered. After a careful clinical review, 50 recurrent TB cases (0.6%) were identified. The overall incidence of recurrence was 113 cases per 100,000 person-years over a median follow up of 6.1 years. For the first 2 years, the incidence of recurrence was over 200/100000. In multivariate analysis of the national cohort, younger age remained an independent risk factor at all time points, and male gender and pulmonary TB at 18 years of follow-up. Among the 50 recurrent cases, 35 patients (70%) had received adequate treatment for the first episode; in 12 cases (24%) the treating physician and in two cases (4%) the patient had discontinued treatment prematurely. In one case (2%) the treatment outcome could not be assessed.

Conclusions

In Finland, the rate of recurrent TB was low despite no systematic directly observed therapy. The first 2 years after a TB episode had the highest risk for recurrence. Among the recurrent cases, the observed premature discontinuation of treatment in the first episode in nearly one fourth of the recurrent cases calls for improved training of the physicians.

Treatment outcome of extra-pulmonary tuberculosis in Finland: a cohort study

BACKGROUND

We investigated the treatments given, the outcome and the patient- and treatment-system dependent factors affecting treatment outcome in a national two-year cohort of culture-verified extra-pulmonary tuberculosis cases in Finland.

METHODS

Medical records of all cases in 1995 - 1996 were abstracted to assess treatment and outcome, using the European recommendations for outcome monitoring. For risk factor analysis, outcome was divided into three groups: favourable, death and other unfavourable. Predictors of unfavourable outcome were assessed in univariate and multivariate analysis.

RESULTS

In the study cohort of 276 cases, 116 (42.0%) were men and 160 (58.0%) women. The mean age was 65.7 years. A favourable outcome was achieved in 157/276 (56.9%) cases, consisting of those cured (8.0%) and treatment completed (48.9%). Death was the outcome in 17.4% (48/276) cases, including cases not treated. Other unfavourable outcomes took place in 45 (16.3%) cases. Significant independent risk factors for death in multinomial logistic regression model were male sex, high age, immunosuppression, any other than a pulmonary specialty being responsible at the end of the treatment and other than standard combination of treatment. For other unfavourable treatment outcomes, significant risk factor was treatment with INH + RIF + EMB/SM. Deep site of TB was inversely associated with the risk of other unfavourable outcome.

CONCLUSIONS

The proportion of favourable outcome was far below the goal set by the WHO. Age and comorbidities, playing an important role in treatment success, are not available in routine outcome data. Therefore, comparisons between countries should be made in cohort analyses incorporating data on comorbidities.