Ahmad et al. BMC Public Health 2012, 12:132 http://www.biomedcentral.com/1471-2458/12/132 HIV prevalence, adoption of the algorithm at frontline health care services, and the adherence of local clini- cians to the algorithm [8]. Several studies have evaluated diagnostic algorithms, mainly focusing on the perfor- mance of the algorithm in diagnosing smear-negative TB among HIV patients [8,9] or in specific settings [10-13]. However, studies that evaluate the implementa- tion and adherence to such algorithms in routine set- tings are lacking, though they would help programme managers identify and correct possible weaknesses in the diagnostic process. The present study evaluated the implementation of the national TB diagnostic algorithm, particularly health providers’ adherence to the standar- dised diagnostic algorithm, in routine health care set- tings in Indonesia. The national TB diagnostic algorithm was adopted from the WHO treatment guidelines, which are designed particularly for application in health centres. The diagnostic algorithm was implemented at the investigated facilities, and most of the medical staff received training and were familiar with the use of this algorithm. Methods Study setting Jogjakarta municipality is an urban area with a popula- tion of approximately half a million. The TB control programme in Jogjakarta municipality relies on a net- work of 18 public health centres, 2 lung clinics, and 9 public and private hospitals. The health centres consist of four microscopy health centres (MHC) capable of performing smear microscopy and 14 satellite health centres (SHC) that collect sputum specimens from TB suspects, prepare smear slides, and send the slides to the MHC for microscopy. The lung clinics have smear microscopy, chest radiography, and VCT services. The incidence of TB in Jogjakarta municipality is estimated to be 63/100,000 [14], and the HIV prevalence among TB patients is estimated to be 1.9% [15]. The TB diag- nosis network is supported by an external quality assur- ance mechanism through quarterly cross-checks by the Provincial Health Laboratory, with technical assistance from the Microbiology Laboratory, Faculty of Medicine, Gadjah Mada University (FM GMU). Data collection and analysis The study took place between November 2009 and May 2010 in all of the public health centres and lung clinics in Jogjakarta municipality. All TB suspects registered at the health centres and lung clinics were included. The definition of TB suspect from the national TB control programme (NTP) guidelines was applied; a patient with a cough for more than 2 weeks was considered a TB suspect, irrespective of HIV status [16]. Diagnostic work-ups, defined as clinical and laboratory Page 2 of 6 examinations, were documented prospectively. The diag- nostic work-up started at the time a patient was consid- ered a TB suspect and continued until the time of diagnosis. A clinical audit form used to record the diag- nostic work-up chronologically, step-by-step was devel- oped and tested prior to data collection. Data on the patient’s gender, age, symptoms, examinations (types, dates, sequence, and results), and final diagnosis were collected. Patients who did not return to their previous health facility, even if they completed the diagnostic work-up, were considered lost and not traced back. A trained nurse filled out the audit form in each facility. A field coordinator conducted monthly supervision visits to check the completeness of the collected data and cross-check it with the patients’ clinical files and the laboratory register. We compared the actual diagnostic work-up with the national TB diagnostic algorithm (Figure 1). All cases that did not match the standardised pathways were cate- gorised as other pathways. All data were double entered into a database checked for typing errors, missing data, and inconsistencies. Data were analysed using SPSS for Windows version 16. Logistic regression was used to analyse factors asso- ciated with patient loss, positivity of TB diagnosis among suspects who completed the diagnostic work-up, and smear positivity of TB cases. Factors were first tested univariately. Factors with P < 0.20 were main- tained using a backward Likelihood Ratio (LR) approach in the multivariate model. Chi-square was used to assess the background characteristics of patients visiting lung clinics and health centres. A median-based test was used to assess differences in the diagnostic delay between lung clinics, MHC, and SHC. Approval was obtained from the ethical committee of FM GMU, Indonesia and the ethics committee of the University of Antwerp, Belgium. Results A total of 724 patients were registered as TB suspects during the study. The majority, 76.5% (n = 554), attended health centres and 23.5% (n = 170) attended lung clinics (Figure 2). The gender and age distribution of patients consulting at health centres and lung clinics was similar (data not shown). Of patients who consulted health centres, 43.5% (n = 241) were lost, but none from the lung clinics were lost. Among patients who com- pleted the diagnostic work-up, adherence to the national TB diagnostic algorithm was 0.0% in lung clinics and 48.9% (n = 153) in health centres. Figure 1 shows a summary of the diagnostic pathways in lung clinics and health centres. Most of the patients (n = 502, 69.7%) started their diagnostic work-up with microscopic sputum smear examination, but only 21.1%