Development of CART model for prediction of tuberculosis treatment loss to follow up in the state of São Paulo, Brazil: A case–control study

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Highlights

  • The CART model develop in this study can predict tuberculosis treatment loss to follow up.

  • As the model is a decision tree it can be used by healthcare professionals to prevent loss to follow up.

  • The Model had an accuracy of 0.76, F-measure of 0.77, sensitivity of 0.80 and specificity of 0.71.

  • The Model emphasizes the relation between several variables already identified in previous studies as related to the patient treatment loss to follow up or cure in the tuberculosis treatment.

Abstract

Background

Tuberculosis is the leading cause of infectious disease-related death, surpassing even the immunodeficiency virus. Treatment loss to follow up and irregular medication use contribute to persistent morbidity and mortality. This increases bacillus drug resistance and has a negative impact on disease control.

Objective

This study aims to develop a computational model that predicts the loss to follow up treatment in tuberculosis patients, thereby increasing treatment adherence and cure, reducing efforts regarding treatment relapses and decreasing disease spread.

Methods

This is a case-controlled study. Included in the data set were 103,846 tuberculosis cases from the state of São Paulo. They were collected using the TBWEB, an information system used as a tuberculosis treatment monitor, containing samples from 2006 to 2016. This set was later resampled into 6 segments with a 1-1 ratio. This ratio was used to avoid any bias during the model construction.

Results

The Classification and Regression Trees were used as the prediction model. Training and test sets accounted for 70% in the former and 30% in the latter of the tuberculosis cases. The model displayed an accuracy of 0.76, F-measure of 0.77, sensitivity of 0.80 and specificity of 0.71. The model emphasizes the relationship between several variables that had been identified in previous studies as related to patient cure or loss to follow up treatment in tuberculosis patients.

Conclusion

It was possible to construct a predictive model for loss to follow up treatment in tuberculosis patients using Classification and Regression Trees. Although the fact that the ideal predictive ability was not achieved, it seems reasonable to propose the use of Classification and Regression Trees models to predict likelihood of treatment follow up to support healthcare professionals in minimising the loss to follow up.

Introduction

Tuberculosis (TB) is the leading cause of infectious disease-related death, surpassing the immunodeficiency virus (HIV) [1]. TB control is based on early and appropriate diagnosis and treatment, interrupting the transmission chain [2]. The National Tuberculosis Control Plan (PNCT) is a strategy implemented by the Brazilian government. The Directly Observed Treatment Short-Course (DOTS), is a part of this strategy and has assisted in the country's reach to an 85% cure rate and has reduced the loss to follow up rate in TB treatments by 5% [2]. However, loss to follow up treatment and irregular medication use contribute to the persistence of morbidity and mortality, increasing drug resistance cases [3], [4].

TB is related to poverty and different social causes. Therefore, patients are difficult to monitor. Factors such as initial improvement, lack of patient follow-up and monitoring are all associated with poor treatment adherence [5]. After the first few months of using the correct medications during treatments, patients present improvements in their overall physical well-being and most of their symptoms are gone, which then leads to patients interrupting the treatment themselves, even though they are not cured. Social factors, treatment methodology and provided health services are factors associated with treatment loss to follow up [6], [7], [8].

In the last 10 years, computational techniques for predicting the outcomes of TB treatment have been explored. Neural networks have been applied to predict the TB treatment loss to follow up in some cities of Espírito Santo in Brazil [9]. A logistic regression model was used to select features [10] and predict loss to follow up TB treatment [5]. Another study compared the application of different machine learning methods to classify treatment outcomes, among which the C4.5 decision tree showed better performance [11].

With a computational model that is able to identify patients that are prone to not follow-up treatment, teams would then be able to focus their efforts in reducing the rate of relapse, dissemination and loss to follow-up treatment. Although there are studies about the subject [9], [10], [5], [11], no study has developed an effective human-readable model that can be applied by health professionals in TB treatment control. Decision trees can be represented as a set of rules that would assist healthcare professionals, the ones with and the ones without access to an information system, to control TB. Thus, this study aims to develop a CART predictive model to predict TB treatment loss to follow up cases.

Section snippets

Materials and methods

For the development of this case-control study, 208,620 TB treatment cases were used, all between the years of 2006 and 2016 and in the state of São Paulo. The sample had sensitive and drug-resistant tuberculosis cases. The state of São Paulo is one of 27 federal states of Brazil and is located in the southeast region of the country. It has 645 cities and an area of 248,219,491 km2 [12]. It has the greatest population in the country, with around 45.9 million inhabitants [12].

The inclusion

Results

The final population of the study contained 91,823 controls and 12,023 cases (Fig. Figure 1 ). Table Table 2 shows the distribution for the population demographic data.

Most of the patients are male adults between the ages of 20 and 39 (24.67%). Less than 2% of the population represents the youth and elders.

The sampled population is mainly composed of white (39.84%) and brown (26.69%) ethnic groups. Only 0.52% of them were from an indigenous ethnic group. Most patients had basic education (less

Discussion

The decision tree created can be used as a guideline among health professionals to detect treatment loss to follow up. The accuracy of the model is similar to other models already presented in the literature [11]. For health professionals, the decision tree is a much more intuitive and understandable approach than a statistical model, since it can be visualized and explored by anyone, as well as be applied without a computational system. To exemplify, the decision tree for this study can be

Conclusion

It was possible to build the predictive model of treatment loss to follow up of tuberculosis through CART. During model development, new features for TB treatment loss to follow up predictors were identified. Although the fact that the ideal predictive ability was not achieved, it seems reasonable to propose the use of CART models. We aim in future studies to improve the model accuracy and implement the model in an informational system for tuberculosis treatment and management.

Summary Points

What was already known on the topic:

  • Treatment loss to follow up and irregular medication use contribute to increased bacillus drug resistance and has a negative impact on disease control.

  • Other studies apply different models to predict the TB treatment outcome.

  • There is evidence that, among different models, decision trees present better performance.

What this study added to our knowledge:

  • The CART model was able to perform equally or better than other models in the literature, additionally

Acknowledgements

We would like to thank the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES) – Finance Code 001 and São Paulo Research Foundation (FAPESP) (Grant Nos. 2018/23963-2 and 2018/00307-2).

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