title: Risk factors for tuberculosis smear non-conversion in Eden district, Western Cape, South Africa, 2007-2013: a retrospective cohort study.
abstract: Tuberculosis (TB) continues to be a major global health problem. While progress has been made to improve TB cure rates, South Africa's 76 % smear-positive pulmonary TB (PTB) case cure rate remains below the WHO target of 85 %. We report on the trends of TB smear non-conversion and their predictors at the end of an intensive phase of treatment, and how this impacted on treatment outcomes of smear-positive PTB cases in Eden District, Western Cape Province, South Africa.
  
  
  
  Routinely collected, retrospective data of smear-positive PTB cases from the electronic TB register in Eden District between 2007 and 2013 was extracted. Non-conversion was defined as persistent sputum smear-positive PTB cases at the end of the two or three month intensive phase of treatment. Chi-square test for linear trend and simple linear regression analysis were used to analyse the change in percentages and slope of TB smear non-conversion rates over time. Risk factors for TB non-conversion, and their impact on treatment outcomes, were evaluated using logistic regression models.
  
  
  
  Of 12,742 total smear-positive PTB cases included in our study, 12.8 % (n = 1627) did not sputum smear convert; 13.3 % (1411 of 10,574) of new cases and 9.9 % (216 of 2168) of re-treatment cases. Although not statistically significant in either new or re-treatment cases, between 2007 and 2013, smear non-conversion decreased from 16.4 to 12.7 % (slope = -0.60; 95 % CI: -1.49 to 0.29; p = 0.142) in new cases, and from 11.3 to 10.8 % in re-treatment cases (slope = -0.29; 95 % CI: -1.06 to 0.48; p = 0.376). Male gender, HIV co-infection and a >2+ acid fast bacilli (AFB) smear grading at the start of TB treatment were independent risk factors for non-conversion (p < 0.001). Age was a risk factor for non-conversion in new cases, but not for re-treatment cases. Non-conversion was also associated with unsuccessful treatment outcomes (p < 0.01), including treatment default and treatment failure.
  
  
  
  Smear-positive PTB cases, especially men and those with identified risk factors for non-conversion, should be closely monitored throughout their treatment period. The South African TB control program should invest in patient adherence counselling and education to mitigate TB non-conversion risk factors, and to improve conversion and TB cure rates.
authors.affiliation: South African Field Epidemiology Training Programme, National Institute for Communicable Diseases, Johannesburg, South Africa.|Epidemiology Research Unit, Foundation for Professional Development, Pretoria, South Africa.|School of Health System and Public Health, University of Pretoria, Pretoria, South Africa.
authors.forename: Mandla
authors.initials: M
authors.lastname: Mlotshwa
authors.affiliation: Epidemiology Research Unit, Foundation for Professional Development, Pretoria, South Africa.
authors.forename: Natasha
authors.initials: N
authors.lastname: Abraham
authors.affiliation: South African Field Epidemiology Training Programme, National Institute for Communicable Diseases, Johannesburg, South Africa.
authors.forename: Moira
authors.initials: M
authors.lastname: Beery
authors.affiliation: South African Field Epidemiology Training Programme, National Institute for Communicable Diseases, Johannesburg, South Africa.
authors.forename: Seymour
authors.initials: S
authors.lastname: Williams
authors.affiliation: Department of Health, George, Western Cape, South Africa.
authors.forename: Sandra
authors.initials: S
authors.lastname: Smit
authors.affiliation: Epidemiology Research Unit, Foundation for Professional Development, Pretoria, South Africa.
authors.forename: Margot
authors.initials: M
authors.lastname: Uys
authors.affiliation: South African Field Epidemiology Training Programme, National Institute for Communicable Diseases, Johannesburg, South Africa.
authors.forename: Carl
authors.initials: C
authors.lastname: Reddy
authors.affiliation: Epidemiology Research Unit, Foundation for Professional Development, Pretoria, South Africa. andrewmedinamarino@gmail.com.|School of Health System and Public Health, University of Pretoria, Pretoria, South Africa. andrewmedinamarino@gmail.com.
authors.forename: Andrew
authors.identifier: 0000-0002-2691-982X
authors.initials: A
authors.lastname: Medina-Marino
mesh_terms: D000328:Adult; D000995:Antitubercular Agents / Q000627:therapeutic use*; D015331:Cohort Studies; D060085:Coinfection / Q000188:drug therapy; D005260:Female; D015658:HIV Infections / Q000382:microbiology; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000187:drug effects*; D012189:Retrospective Studies; D012307:Risk Factors; D013019:South Africa; D013183:Sputum / Q000187:drug effects / Q000382:microbiology*; D017211:Treatment Failure; D016896:Treatment Outcome; D014397:Tuberculosis, Pulmonary / Q000175:diagnosis / Q000188:drug therapy* / Q000382:microbiology
chemical_list: D000995:Antitubercular Agents
keywords: Risk factors; Smear non-conversion; South Africa; Treatment outcomes; Trends; Tuberculosis