Cost-effectiveness of educational outreach to primary care nurses to increase tuberculosis case detection and improve respiratory care: economic evaluation alongside a randomised trial

Authors


Corresponding Author Max O. Bachmann, School of Medicine, Health Policy and Practice, University of East Anglia, Norwich NR4 7TJ, UK. E-mail: m.bachmann@uea.ac.uk

Summary

Objective  To evaluate the cost-effectiveness of an educational outreach intervention to improve primary respiratory care by South African nurses.

Methods  Cost-effectiveness analysis alongside a pragmatic cluster randomised controlled trial, with individual patient data. The intervention, the Practical Approach to Lung Health in South Africa (PALSA), comprised educational outreach based on syndromic clinical practice guidelines for tuberculosis, asthma, chronic obstructive pulmonary disease, pneumonia and other respiratory diseases. The study included 1999 patients aged 15 or over with cough or difficult breathing, attending 40 primary care clinics staffed by nurses in the Free State province. They were interviewed at first presentation, and 1856 (93%) were interviewed 3 months later.

Results  The intervention increased the tuberculosis case detection rate by 2.2% and increased the proportion of patients appropriately managed (that is, diagnosed with tuberculosis or prescribed an inhaled corticosteroid for asthma or referred with indicators of severe disease) by 10%. It costs the health service $68 more for each extra patient diagnosed with tuberculosis and $15 more for every extra patient appropriately managed. Analyses were most sensitive to assumptions about how long training was effective for and to inclusion of household and tuberculosis treatment costs.

Conclusion  This educational outreach method was more effective and more costly than usual training in improving tuberculosis, asthma and urgent respiratory care. The extra cost of increasing tuberculosis case detection was comparable to current costs of passive case detection. The syndromic approach increased cost-effectiveness by also improving care of other conditions. This educational intervention was sustainable, reaching thousands of health workers and hundreds of clinics since the trial.

Abstract

Rapport coût-efficacité de l’assistance éducative des infirmier(e)s en soins primaires pour accroître le dépistage des cas de tuberculose et améliorer les soins respiratoires: évaluation économique au cours d’un essai randomisé

Objectif:  Evaluer le rapport coût-efficacité d’une intervention d’assistance éducative visant à améliorer les soins primaires respiratoires par les infirmier(e)s sud-africaines.

Méthodes:  Analyse coût-efficacité au cours d’un essai pragmatique randomisé contrôlé en grappe, avec des données individuelles de patients. L’intervention - ‘Approche Pratique de la Santé Pulmonaire en Afrique du Sud (PALSA)’- comprenait l’assistance éducative basée sur les directives de pratique clinique syndromique pour la tuberculose, l’asthme, la broncho-pneumopathie chronique obstructive, la pneumonie et autres maladies respiratoires. L’étude a inclus 1999 patients âgés de 15 ans ou plus avec une toux ou une difficulté respiratoire, visitant 40 cliniques de soins primaires dotées d’infirmier(e)s dans la Province du Free State. Ils ont été interviewés lors de la première présentation et 1856 (93%) d’entre eux ont été interviewés trois mois plus tard.

Résultats:  L’intervention a augmenté de 2,2% le taux de détection des cas de tuberculose et de 10% la proportion de patients pris en charge de façon appropriée (i.e. diagnostic de la tuberculose, prescription d’un corticostéroïde inhalé pour l’asthme ou référé avec des indicateurs de maladie grave). Cela a coûté au service de santé 68 $ de plus pour chaque patient supplémentaire diagnostiqué avec la tuberculose, et 15 $ de plus pour chaque patient supplémentaire convenablement pris en charge. Les analyses ont été plus sensibles pour les hypothèses sur la durée au cours de laquelle la formation était efficace et sur l’inclusion des coûts des ménages et du traitement de la tuberculose.

Conclusion:  Cette méthode d’assistance éducative a été plus efficace et plus coûteuse que la formation habituelle sur l’amélioration des soins pour la tuberculose, l’asthme et les affections respiratoires urgentes. Le coût supplémentaire pour l’augmentation de la détection des cas de tuberculose était comparable aux coûts actuels de détection passive de cas. L’approche syndromique a augmenté la rentabilité en améliorant également les soins pour les autres conditions. Cette intervention éducative était durable, atteignant des milliers d’agents de la santé et des centaines de cliniques depuis l’étude.

Abstract

Análisis de coste-efectividad del alcance educativo entre enfermeras de cuidados primarios a la hora de aumentar la detección de casos de tuberculosis y mejorar los cuidados respiratorios: evaluación económica paralela a un ensayo aleatorizado

Objetivo:  Evaluar la relación coste/efectividad del alcance de una intervención educativa para mejorar la atención primaria en cuidados respiratorios de enfermeras Sudafricanas.

Métodos:  Análisis de coste-efectividad con datos de pacientes individuales paralelo a un ensayo controlado, aleatorizado, de conglomerados. La intervención, PALSA (por sus siglas en inglés Practical Approach to Lung Health in South Africa), incluía un programa educativo basado en las guías de práctica clínica sindrómica para tuberculosis, asma, enfermedades pulmonares obstructivas crónicas, neumonía y otras enfermedades respiratorias. El estudio incluía 1999 pacientes con edades comprendidas entre los 15 años o más, con tos o dificultad respiratoria, que se presentaron en 40 centros de atención primaria atendidos por enfermeras en la provincia del Estado Libre. Se les entrevistó durante la primera cita y 1856 (93%) fueron entrevistados tres meses después.

Resultados:  La intervención aumentó la tasa de detección de los casos de tuberculosis en un 2.2% y aumentó en un 10% la proporción de pacientes con un manejo apropiado (es decir, diagnosticados con tuberculosis o que recibieron prescripción de corticoesteroides inhalados para el asma o fueron referidos al tener indicadores de una enfermedad severa.) Al servicio sanitario le costó$68 más por cada paciente extra diagnosticado con tuberculosis, y $15 más por cada paciente extra manejado de forma apropiada. Los análisis fueron sobre todo sensibles a los supuestos sobre durante cuanto tiempo era efectivo el entrenamiento y sobre la inclusión de los costes de los hogares y del tratamiento de la tuberculosis.

Conclusión:  Este método de alcance educativo fue más efectivo y más costoso que el entrenamiento usual en el manejo de la tuberculosis, el asma y los cuidados respiratorios urgentes. El coste extra de aumentar la detección de casos de la tuberculosis era comparable con los costes actuales de la detección pasiva de casos. El enfoque sindrómico aumentó la coste efectividad mejorando también los cuidados y otras condiciones. Esta intervención educativa era sostenible, llegando a miles de trabajadores sanitarios y cientos de clínicas durante el ensayo.

Introduction

The World Health Organization (WHO) has estimated that a fifth of primary care consultations in developing countries are because of respiratory symptoms and that 2% of primary care patients have tuberculosis (WHO 2004). WHO and developing country health services have increased efforts to improve tuberculosis case detection because of increasing tuberculosis incidence, aggravated by HIV and antibiotic resistance (Gandhi et al. 2006, WHO 2008a,b). They are also increasingly trying to integrate tuberculosis care with primary care for other chronic diseases.

In South Africa, most patients with respiratory symptoms are treated in public sector primary care clinics by nurses who have little training in diagnosis and treatment of respiratory disease. Among such patients, tuberculosis is often not diagnosed (WHO 2008b), asthma is under-treated (Mash & Whittaker 1997; Stempel et al. 2004) and antibiotics are over-prescribed (Louwagie et al. 2002, WHO 2004). South Africa’s tuberculosis notification rates more than doubled between 2000 and 2007 (WHO 2009). Thus, an effective and sustainable method of training primary care nurses to diagnose and treat respiratory disease is needed.

World Health Organization’s Practical Approach to Lung Health (PAL) strategy aims to increase detection of active tuberculosis among adults with cough or difficulty breathing, and also to improve the diagnosis, treatment and referral of other respiratory conditions, through integrated clinical management of patients presenting to first-level facilities with respiratory symptoms (WHO 2005, 2008b). Similar syndromic approaches have been used for other diseases in developing countries, with some evidence of cost-effectiveness (Gilson et al. 1997; Adam et al. 2005; Shresta et al. 2006).

The Practical Approach to Lung Health in South Africa (PALSA) combines locally adapted syndromic guidelines with evidence-based methods of educational outreach delivered by usual health department trainers (Bheekie et al. 2006; English et al. 2008). An important advantage over conventional classroom-based methods of educating professionals is that it is brief and does not remove scarce primary care staff from their workplaces. A pragmatic cluster randomised controlled trial conducted in 2003 showed that PALSA significantly improved the quality of respiratory and tuberculosis care, increasing tuberculosis case detection, asthma treatment and appropriate urgent referral among patients attending clinics staffed by nurses in a resource-poor rural province of South Africa (Fairall et al. 2005). We have shown elsewhere that the guideline, when used by a nurse, was accurate in identifying patients at high risk of pulmonary tuberculosis (English et al. 2006). The present study evaluates PALSA’s cost-effectiveness.

Methods

We analysed cost-effectiveness alongside a pragmatic cluster randomised trial, using cost and outcome data about individual patients. The study had a societal perspective, considering the costs of illness to the health service and to the society for the period from the first consultation until 3 months later. We included societal as well as health service perspectives, because costs of illness and health care use can be considerable for patients, their households and society, especially for chronic disabling diseases such as tuberculosis and obstructive lung disease, and these costs could be influenced by better care.

Intervention and trial

The Free State province’s 40 largest primary care clinics outside the capital were randomised to receive the PALSA intervention or to continue with usual training and support. The intervention was based on the PALSA syndromic guideline for management of adult respiratory diseases (Fairall et al. 2005; English et al. 2008), which classified patients into diagnostic and treatment categories according to their symptoms and signs. It covered tuberculosis, obstructive lung disease, acute upper and lower respiratory tract infections and HIV opportunistic infections. It was adapted from WHO’s PAL guideline (WHO 2005, 2008b), after consultation with South African primary care physicians, nurses and managers, and harmonised with local guidelines such as the national essential drug list, HIV and tuberculosis programmes. The guideline was published in booklet and desk blotter formats (English et al. 2006).

Primary care nurses were trained to use the PALSA guideline at their clinics, to minimise disruption of services. The programme trained eight nurse managers already employed by the health department, who then trained the nurses. Each trainer delivered three or four educational outreach sessions, each lasting 1–3 h, to all clinical staff in each intervention clinic over a 3-month period. Key messages as, ‘With cough or difficulty breathing for two weeks or more, think of tuberculosis’ were emphasised.

The study recruited 1999 patients with cough or difficult breathing attending the trial clinics. After randomisation, the trial arms had equal numbers of clinics in each district, equal proportions of urban and rural clinics and similar numbers of tuberculosis patients per clinic treated during the previous year. Numbers of patients recruited per clinic ranged from 47 to 51 in intervention clinics and from 46 to 51 in control clinics. Patients in intervention and control clinics had similar baseline characteristics (Fairall et al. 2005). They were interviewed after their first consultation and again 3 months later, so the study’s follow-up period was 3 months. At follow-up, 1856 (93%) patients were interviewed. The trial took place between May and November 2003, implemented incrementally as training was rolled to each district. All 20 clinics randomised to receive the intervention did receive it, and therefore all 1000 trial patients in intervention clinics were potentially exposed to the intervention.

Outcome measurements

We defined two primary trial outcomes at the initial consultation or within 3 months: tuberculosis case detection and ‘appropriate care’. Tuberculosis case detection was defined as a new diagnosis of tuberculosis, confirmed by examination of patient-held tuberculosis treatment records. In keeping with national policy, tuberculosis could only be diagnosed if sputum smear tests identified tubercle bacilli or, for smear negative cases, if a medical doctor had made a clinical diagnosis, using all available clinical evidence including radiography and sputum culture results. Thus, all new tuberculosis diagnoses recorded were by definition true positive cases. ‘Appropriate care’ was defined as (i) new tuberculosis diagnosis or (ii) treatment with inhaled corticosteroids for asthma or (iii) referral for a higher level of care in the presence of defined indicators of severe illness (respiratory rate ≥30 breaths per min, temperature ≥38 °C, prominent use of accessory muscles, or confusion). Asthma treatment and urgent referral were established by patient interview and examination of patients’ medical records. The intervention’s effects were the differences between arms in these outcomes.

Cost of the educational intervention

Costs of developing the guideline and training materials were estimated from project expenditure records, diary reviews and interviews with the developers (Table 1). Clinic staff training costs were obtained from attendance registers completed by trainers, and records of session duration, transport and other costs associated with training. The hours each person spent developing, delivering or receiving the intervention were multiplied by their respective hourly costs to their employers. The effects of training were assumed to last only for the 3 months of follow-up during the trial, so all training costs were allocated to this period.

Table 1.   Cost of developing, delivering and receiving the training intervention
Total cost of the PALSA intervention
CategoryCost (2009 $US)Resources used
  1. PALSA, Practical Approach to Lung Health in South Africa.

  2. †Development costs incurred before 2003 were inflated to 2009 values using the average South African consumer price index.

  3. ‡Costs were allocated to patient attendances using routine data on total clinic attendances and assuming 30% (51 797) of all 172 636 patients who attended trial clinics during the trial had cough or difficult breathing and could have benefited from the intervention.

Guideline development†96 49911 months’ of junior and 2 months’ of senior researcher time, 1 month of health care worker time, 6 days WHO consultants’ time; cost of workshops including 10 local and 2 international flights, accommodation and venues; graphic layout
Training programme and materials development54 9017 months’ of junior and 2 months’ of senior researcher time, 0.5 month of health care worker time; cost of pilot sessions including four local flights, accommodation and venues; illustrations and graphic layout
Training the trainers31 7740.5 month junior and 0.5 month senior researcher time, 3 months health care worker time; 11 local flights, accommodation and road travel; support materials for trainers
Educational outreach visits15 94060 educational outreach visits to 148 nurses in 20 clinics including 49 months of health care worker time, travel (6569 km) and materials
Total cost of PALSA199 113 
Cost of intervention per clinic attendance‡
CategoryCost in 2009 $USComments
Guideline and material development0.12Development costs of guideline and training programme were treated as capital costs, allocated over 6 years
Training trainers and outreach visits1.04100% allocated to intervention clinics assuming training was not used elsewhere or after the trial endpoint
Total cost of intervention per attendance1.15 

Resources used in developing the guideline and training materials were considered as a capital cost. Assuming that the guideline and training materials would remain valid for 6 years, based on other guideline research (Shekelle et al. 2001), we allocated 4.2% (3 months/6 × 12 months) of these capital costs to the 3 months of follow-up in each clinic during the trial. These guidelines were still in use in 2009 but had been expanded to cover other diseases. We assumed that 30% of all clinic patients during the 3-month trial period had respiratory symptoms and could have benefited from the intervention, based on our previous study in a similar setting (Fairall et al. 2001). Development and training costs per clinic attendance by a PALSA-eligible patient were then estimated by dividing these total costs by 30% of the total number of clinic attendances recorded during the trial period (Table 1).

Patients’ resource use, unit costs and total costs of resources

Information on patients’ health care use was collected through an interviewer-administered questionnaire at baseline and 3 months later (Table 2). It elicited information on numbers of clinic visits, investigations performed, drugs prescribed, numbers and duration of hospital admissions, ambulance transport, private sector health practitioners’ fees, patients’ transport costs and other episode-related out-of-pocket expenditure.

Table 2.   Use of health care resources and mean costs (in 2009 US$) per patient during 3 months of follow-up
ResourcesUnit cost ($)InterventionControlSource of unit costs
Mean no. unitsMean cost ($)Mean no. unitsMean cost ($)
  1. FS DOH, Free State Department of Health; PALSA, Practical Approach to Lung Health in South Africa.

Health service costs
 Public health service utilisation
  Clinic visits14.161.5121.461.4220.13Daviaud (1999)
  Outpatient visits11.290.050.620.040.50Haile (2000)
  Inpatient days42.520.135.450.218.87Cleary et al. (2004)
  Ambulance trips95.840.043.970.055.21FS DOH
 Medication
  Beta-agonists 0.401.540.260.98FS DOH
  Inhaled corticosteroids 0.151.040.080.52FS DOH
  Antibiotics (excluding TB drugs) 0.570.700.540.65FS DOH
  Other drugs 0.821.760.781.12FS DOH
 Investigations
  Sputum tests for TB5.020.733.660.552.74FS DOH
  Chest X-ray7.250.090.650.060.40FS DOH
  HIV rapid test kits2.840.100.280.080.22FS DOH
  PALSA intervention costs1.151.511.73 0.00Table 1
Total health service costs  42.83 41.34 
Household costs
 Fees paid to private providers  5.15 4.10 
 Travel to the clinic  1.41 0.89 
 Travel to other HCP  1.64 1.11 
Total household costs  8.20 6.07 
Total societal costs  51.03 47.40 

Unit costs of resources were obtained from pharmaceutical services, laboratory tariffs, department of health tariffs and a literature review (Table 2). We conducted a work study of 433 consultations by adult patients with cough or difficulty breathing with nurses in 10 intervention and 9 control clinics. This showed no difference in duration of consultations. To calculate the total cost of resources used, for each resource the unit cost was multiplied by the respective number of resources used.

As the trial was conducted in 2003, earlier development costs were inflated to 2003 values (Statistics South Africa 2009). Discounting of costs and outcomes after 2003 was unnecessary because the study was confined to 2003. Costs were converted from South African rands to United States dollars using the average exchange rate for the trial period ($1 = ZAR 7.35), then adjusted for inflation to 2009 United States dollars (United States Department of Labor 2009).

Cost-effectiveness analysis

This analysis used patient level data on costs and outcomes from the trial, described previously. We calculated incremental cost-effectiveness ratios (ICERs) for both primary outcomes (tuberculosis case detection and appropriate care) in an intention-to-treat analysis. The ICER represents the average extra cost for each additional patient who attains the respective, beneficial, outcome. ICER point estimates were calculated by dividing differences in mean costs by differences in outcome probabilities.

Statistical analysis of individual patient data was conducted as follows. Regression models were used to compare trial arms while accounting statistically for cluster randomisation within strata. The mean effects and cost differences were obtained from regression models, and ICER confidence intervals and probabilities that the intervention was cost-effective were obtained from bootstrap analyses. Differences in mean costs between the two trial arms were estimated with linear regression. Differences in outcomes were estimated with binomial logistic regression. In all regression models, district as well as trial arm were included as explanatory variables, because randomisation was stratified by district. Patients’ characteristics were not included as model covariates because, owing to randomisation, they were not confounders (Fairall et al. 2005). Clinics were not included as covariates because they were completely collinear with arm. Regression analyses used Huber–White robust adjustment for intra-clinic correlation.

We used non-parametric bootstrap sampling to quantify statistical uncertainty and to account for intra-clinic clustering of costs and outcomes (Carpenter & Bithell 2000). We drew 2000 iterations per analysis, first sampling clinics within arms and then sampling individuals within clinics, both with replacement (Bachmann et al. 2007). We used the bias-corrected accelerated percentile method to estimate ICER confidence intervals (Carpenter & Bithell 2000). Bootstrap sampling resulted in scatter plots of differences in cost and outcomes, showing the uncertainty about effects and differences in mean cost per patient (Figures 1 and 2). We disregarded ICER confidence intervals from analyses of tuberculosis case detection, because they included some samples worse with outcomes and higher costs as well as others with better outcomes and lower costs (Figure 1). In such situations, confidence limits cannot be interpreted (Briggs 2001).

Figure 1.

 Cost-effectiveness plane with additional cases of tuberculosis diagnosed as effect.

Figure 2.

 Cost-effectiveness plane with additional patients appropriately managed as effect.

We plotted cost-effectiveness acceptability curves, showing the probability (y-axis) that the intervention is cost-effective for various acceptability thresholds (x-axis) (Briggs 2001). Briefly, this analysis is based on the equation:

nb = eλ − c

where nb is the net benefit of an intervention, e is the effect of the intervention, λ is the amount society is willing to pay for a unit of effect and c is the extra cost of the intervention. As λ is not known in this context, a range of values are used. The intervention is cost-effective if  > c. This is determined for each bootstrap sample, for a range of λ values, and the probability that the intervention is cost-effective at each λ values is the proportion of bootstrap samples for which  > c. Statistical analyses were conducted with stata 9.0 (STATA Corp.,).

We conducted several sensitivity analyses to test the robustness of our findings. First, we halved training costs, reflecting a scenario where the training was effective for 6 instead of 3 months. Secondly, for newly diagnosed tuberculosis cases, we included costs of tuberculosis treatment during the whole period of follow-up. Thirdly, we changed other key parameters to 50% and 150% of their assumed values in the base case analysis. These parameters included the proportions of all clinic patients assumed to have cough or difficulty breathing, unit costs of health service resources and depreciation of the guideline and training materials.

Ethics approval

The study was approved by the research ethics committee of the Faculty of Health Sciences, University of the Free State.

Results

Effects of the intervention

The trial (Fairall et al. 2005) found that tuberculosis was newly diagnosed in 4.5% of intervention arm patients and 2.3% of control arm patients (risk difference 2.2%, 95% confidence interval (CI) 0.4–4.1%; P = 0.03). Appropriate care was recorded in 20.8% of intervention arm patients and 10.8% of control arm patients (risk difference 10.0, 95% CI 4.9–15.0; P < 0.001). The 10.0% risk difference for appropriate care included risk differences of 2.2% for tuberculosis case detection, 3.1% (7.8%vs. 4.7%) for urgent referrals and/or 6.0% (13.7%vs. 7.7%) for inhaled corticosteroid prescriptions.

Costs of the intervention and of provision and utilisation of health care

The total cost of the training intervention was $199 113 (Table 1). Of this, the cost of developing the guideline and materials was $151 400, and 4.2% of this was allocated to the 3 months of the trial. Training sessions cost $47 713, all of which was allocated to the 3 months of the trial. The training intervention thus cost an average of $1.15 per patient clinic visit (Table 1). Intervention group patients visited clinics on average 1.51 times during the trial, so the intervention alone cost on average $1.73 per intervention group patient (Table 2).

In the primary analysis, the intervention was associated with a $1.49 (95% CI $6.38–$9.37) higher mean health service cost and a $3.64 (95% CI $4.37–$11.65) higher mean societal cost, compared with usual care. These differences were largely because of more clinic visits, tuberculosis tests, asthma medication and greater costs of travel and private providers, despite lower inpatient and ambulance costs among intervention arm patients (Table 2). When we included costs of tuberculosis treatment after diagnosis for the period of follow-up, the mean health service cost was $3.00 (95% CI $4.88–$10.92) higher in the intervention arm than the control arm. When we allocated only half of training costs to the 3-month trial period, the mean health service cost was $0.73 (95% CI $7.10–$8.54) higher in the intervention arm. When unit costs of each resource item were increased or decreased by 50%, the differences in mean cost (and thus ICERs) were most sensitive to changes in unit costs of inpatient days (cost differences increased or decreased by 58%), ambulance trips (by 26%) and sputum smear tests (by 15%), and by <10% for all other items.

Cost-effectiveness of the intervention

In the primary analysis, the intervention was associated with a $68 higher health service cost, and a $166 higher total societal cost, per extra tuberculosis case diagnosed (Table 3). It was associated with a $15 higher health service cost, and a $36 higher total societal cost, per extra patient appropriately managed. Cost-effectiveness estimates were sensitive to inclusion of tuberculosis treatment costs and assumptions about how long training was effective for (Table 3).

Table 3.   Sensitivity analysis: incremental cost-effectiveness ratios (ICERs) when different outcomes and costs are considered
Costs consideredOutcome considered
Tuberculosis diagnosed ICER† [% of base estimate]Appropriate care‡ ICER (95% CI) [% of base estimate]
  1. CI, confidence interval.

  2. †Negative confidence limits not interpretable because they include bootstrap samples having worse outcome with higher costs, and others having better outcomes with lower costs (Figure 1).

  3. ‡Tuberculosis diagnosed or preventive asthma treatment or appropriate urgent referral.

Base health service cost67.89 [100]14.91 (−97.59, 146.94) [100]
Societal (health service and household) cost165.11 [243]36.44 (−92.41, 141.15) [144]
Health service cost allocating training costs over 6 instead of 3 months32.61 [49]7.25 (−65.07, 151.68) [49]
Health service cost including tuberculosis treatment137.11 [202]30.21 (4.18, 75.13) [203]

The cost-effectiveness acceptability curves show that, when increases in appropriate care were considered (Figure 3), the intervention appeared much more likely to be cost-effective at any willingness to pay threshold, compared to analyses with tuberculosis case finding as outcome (Figure 4). In the latter analyses, there was wide variation in the acceptability thresholds for which the intervention would be cost-effective (Figure 3). This reflects the greater statistical uncertainty about the intervention’s effect on tuberculosis case finding alone (Figure 1), together with uncertainty about costs.

Figure 3.

 Cost-effectiveness acceptability curves for tuberculosis case detection, with different costs considered.

Figure 4.

 Cost-effectiveness acceptability curves for appropriate care, with different costs considered.

Discussion

The study shows that the PALSA educational outreach intervention costs more, and was more effective, than usual training and support. The extra cost of $68 per extra tuberculosis case detected is similar to the cost of passive case finding in South African clinics, previously estimated at $39 per case diagnosed in 1997 (Sinanovic et al. 2003), or $67 at 2009 prices (US Department of Labor 2009). The extra cost would therefore probably be acceptable to South African health services, although costs of enhanced case finding would be additional to current costs of passive case finding. It compares favourably with an earlier South African study’s finding that enhanced case finding cost $166 per extra case detected (Hausler et al. 2006). The intervention is more cost-effective if one also considers its additional effects on asthma and severe respiratory illness.

The cost-effectiveness of the intervention would be much better than we estimated if training effects lasted longer than the 3 months we conservatively assumed (Table 3) and reached more trainees. Other studies (Sanci et al. 2000; Morgenstern et al. 2003) have shown that educational outreach training can last longer than 3 months. As this study PALSA has been expanded to cover HIV/AIDS and implemented in four provinces of South Africa, reaching over 6000 health workers in about 900 clinics. During province-wide implementation, each trainer was assigned twice as many clinics as in the trial. With large-scale implementation, the marginal costs of the guideline and educational materials would have decreased.

Modelling studies have shown that increasing tuberculosis case detection is the most cost-effective way to control tuberculosis in countries with high HIV prevalence (Baltussen et al. 2005, Currie et al. 2005). However, there is minimal evidence identifying effective and cost-effective ways of increasing tuberculosis case detection (Golub et al. 2005). To our knowledge, PALSA is the first educational intervention with randomised trial evidence of improved tuberculosis case detection in Africa. To evaluate PALSA’s effects on future tuberculosis transmission and death, one needs to consider evidence from other studies. A WHO modelling study estimated that a 1% increase in case detection and treatment in South Africa would prevent 29000 new cases and 22000 deaths between 2000 and 2009 (Currie et al. 2003). That is equivalent to preventing 0.97 new cases and 0.73 deaths for every extra case detected, assuming an average of 300 000 cases detected every year without PALSA (Currie et al. 2003). The incremental health service cost of PALSA would thus be $70 per case prevented or $93 per death prevented, excluding tuberculosis treatment costs. If health services costs of treating extra cases detected and prevented are included, and assumed to average $500 per case (Sinanovic et al. 2003), then the incremental health service costs of PALSA would be $92 per new case of active tuberculosis prevented and $269 per death prevented (not considering costs saved by preventing deaths).

The study is an advance on other economic evaluations of similar interventions because it is based on a large rigorous randomised controlled trial with detailed data on patients’ costs and outcomes. However, the study has several limitations. First, the short duration of follow-up meant that long-term costs and health outcomes which are relevant to chronic diseases such as tuberculosis and asthma could not be measured. Second, the three effects grouped together as ‘appropriate care’ were given equal weights to produce this composite outcome. We could instead have used different, subjective, weights or more complex statistical methods for composite outcomes (Bjorner & Keiding 2004; Negrı & Vazquez-Polo 2006). However, interpreting such results would be less straightforward. Finally, the absence of an accepted acceptability or willingness to pay threshold for these particular outcomes means that one cannot make a straightforward decision about whether or not the intervention is cost-effective from this study alone.

This study shows that, although the intervention increased costs in the short term, it could be cost-effective, depending on how much funders were willing to pay for better care. These results cannot automatically be generalised to other countries. However, they show that carefully developed and implemented clinical practice guidelines, with educational outreach, can improve tuberculosis case detection and other primary respiratory care at affordable cost. This supports global efforts such as PAL to improve and integrate the primary health care of adults in developing countries.

Acknowledgements

We thank the Free State Department of Health nurse trainers: Leona Smith, Annette Exley, Sandra Korkie, Tebogo Mothibeli, Francis MacKay, Elizabeth Bolofo and the late Mariana Thirtle; Ineke Buskens for training the nurse trainers; fieldwork supervisors Mariëtte van Rensburg and Gloria Gogo, Centre for Health Systems Research and Development, University of the Free State; Michael Wyeth and Val Myburgh for training materials design; Chris Seebregts and Clive Seebregts, Medical Research Council (MRC), for data management; Chrismara Güttler and Amanda Fourie, MRC for data capture; Sonja Botha for data editing; Sonja van der Merwe and Annette Furter from the Free State Department of Health for arranging pilot sessions and providing routine data; and Miranda Mugford, University of East Anglia for methodological advice. Victor Lithlakanyane and Mosiuoa Shuping, Free State Department of Health; European Union-funded AfroImplement and PRACTIHC collaborations; and Refiloe Matji, formerly South African National tuberculosis control programme, provided early support and advice. Robert Scherpbier and Salah-Eddine Ottmani, WHO, conceptualised PAL which is the basis of PALSA’s screening and syndromic approaches. The WHO-led multi-country PAL evaluation includes studies in Chile, Kyrgyzstan, Morocco, South Africa and Nepal.

This research programme was funded by the International Development Research Centre, Canada, the South African Medical Research Council, the Free State Department of Health and the University of Cape Town Lung Institute. The authors declare that they had full control of all primary data and did not enter an agreement with funders that may have limited their ability to complete the research as planned.

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