| Summary: | 博士 === 國立臺灣大學 === 流行病學與預防醫學研究所 === 106 === ABSTRACT
Background: Infectious pulmonary tuberculosis (TB) patients are universally expected to initiate therapy promptly after diagnosis in order to quickly halt the transmission of TB within any community. In reality, not all these diagnosed cases finally initiate TB therapy; hence, they become what is known as pre-treatment loss to follow-up (PLTFU) patients. Current figures of PLTFU range between 4 and 38% with great geographic heterogeneity. We aimed to investigate the proportion and risk factors of PLTFU of TB patients and the reasons of PLTFU in two regions of Cameroon. We also evaluated the impact of patient counseling and phone reminder on PLTFU.
Methods: The three studies conducted include a retrospective (Jul-Dec 2015), prospective (Feb-Jul 2016) and an impact evaluation study, involving thirty-nine TB diagnostic and treatment units (DTUs). Pre-prepared data collection forms and semi-structured questionnaires were used to retrieve information from TB laboratory and treatment registers for all bacteriologically confirmed cases diagnosed during the study period. Data retrieved from both TB registers were cross-linked to identify any PLTFU cases (defined by failure to initiate treatment 7 days after diagnosis). Socio-demographic, sputum examination results and treatment information were collected. Travel distance/travel time between patient’s residence and DTU’s location were obtained using geographic information system tools. In the prospective study, all confirmed TB patients received counseling on the importance of treatment and the objectives for the study. Those who did not return for treatment on time were further contacted by phone or messages. Reasons for loss to follow-up were inquired and the patients were reminded to return for treatment. In the retrospective and prospective studies, we conducted univariable and multivariable logistic regression analyses to determine the risk factors of PLTFU. We also conducted Cox proportional hazard regression to determine the determinants of time to treatment in these patients. To evaluate the intervention of patient counseling and phone reminder (which was implemented in the prospective study), we combined the retrospective and prospective studies. Univariable and multivariable logistic regression analyses of the merged data were conducted to determine whether the intervention was associated with PLTFU, adjusting for other risk factors. We also performed a regression discontinuity analysis by adding a linear term of time trend and an interaction term between the intervention and the linear term of time trend to the logistic regression model.
Results: In the retrospective study, 1174 cases of bacteriologically confirmed TB were identified. The PLTFU proportion was 16.7% (95% CI: 14.6- 18.8%) in these patients. Median time from first positive TB result to therapy initiation was two days (IQR: 2–3). In the multivariable logistic regression, significant risk factors for PLTFU included urban DTUs ([urban versus rural], adjusted odds ratio (aOR): 2.51, 95% CI: 1.51–4.17); travel time from home to DTUs (>30 minutes versus ≤30.0 minutes, aOR: 2.19, 95% CI: 1.56–3.09); and travel distance from home to DTU (>30 km versus ≤30.0 km, aOR: 2.31, 95% CI: 1.63–3.27). In the multivariable Cox regression, significant determinants of time to treatment included urban DTUs ([urban versus rural], adjusted hazards ratio (aHR): 0.72, 95% CI: 0.60–0.86); travel time from home to DTUs (>30 minutes versus ≤30.0 minutes, aHR: 0.80, 95% CI: 0.69–0.92); and travel distance from home to DTU (>30 km versus ≤30.0 km, aHR: 0.76, 95% CI: 0.66–0.89).
In the prospective study, 1060 cases of bacteriologically confirmed TB were identified, and 10.6% (95% CI: 8.7–12.4%) had PLTFU. Risk factors for PLTFU and determinants of time to treatment in the prospective study were similar to those in the retrospective study. Major reasons for loss to follow-up included lack of transport money to get back to hospital (50%), DTU was too far away from home (29.3%), and 14.6% had travelled out of town.
In the impact evaluation study, patient counseling and phone reminder was associated with reduced odds of PLTFU both in the univariable (odds ratio [OR]: 0.56; 95% CI: 0.44–0.72) and multivariable (OR: 0.61; 95% CI: 0.47–0.79) analysis. In the regression discontinuity analysis using logistic regression, the association between the intervention and PLTFU was not statistically significant (aOR: 0.71, 95% CI 0.25–2.01), and the associations for the linear time trend (aOR: 0.999, 95% CI 0.996– 1.002) per day; and for the interaction between intervention and time (aOR: 1.0001, 95% CI 0.996–1.005) were not significant either.
Conclusion: Access to TB treatment following diagnosis was still a major problem in Cameroon. This may be hampered by risk factors related to the patients and the TB care providers. The presence of PLTFU introduced a significant barrier to TB control. Measures such as adequate pre-and post-diagnosis counselling and phone call reminders may have a positive effect on reducing PLTFU, but their effectiveness needs to be assessed in subsequent studies.
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