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Research Article

# Cost-Effectiveness Analysis of Three Leprosy Case Detection Methods in Northern Nigeria

• ccezenduka@yahoo.co.uk

Affiliations: Health Policy Research Group, Department of Pharmacology and Therapeutics, College of Medicine, University of Nigeria, Enugu, Nigeria, Department of Clinical Pharmacy and Pharmacy Management, Nnamdi Azikiwe University, Awka, Nigeria

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• Affiliation: Royal Tropical Institute (KIT), Amsterdam, The Netherlands

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• Affiliation: State Tuberculosis and Leprosy Control Programme (STBLCP), Yola, Nigeria

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• Affiliation: State Tuberculosis and Leprosy Control Programme (STBLCP), Gombe, Nigeria

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• Affiliation: Netherlands Leprosy Relief (NLR), Jos, Nigeria

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• Affiliations: Health Policy Research Group, Department of Pharmacology and Therapeutics, College of Medicine, University of Nigeria, Enugu, Nigeria, Department of Health Administration and Management, University of Nigeria, Enugu, Nigeria

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• Published: September 20, 2012
• DOI: 10.1371/journal.pntd.0001818

## Abstract

### Background

Despite several leprosy control measures in Nigeria, child proportion and disability grade 2 cases remain high while new cases have not significantly reduced, suggesting continuous spread of the disease. Hence, there is the need to review detection methods to enhance identification of early cases for effective control and prevention of permanent disability. This study evaluated the cost-effectiveness of three leprosy case detection methods in Northern Nigeria to identify the most cost-effective approach for detection of leprosy.

### Methods

A cross-sectional study was carried out to evaluate the additional benefits of using several case detection methods in addition to routine practice in two north-eastern states of Nigeria. Primary and secondary data were collected from routine practice records and the Nigerian Tuberculosis and Leprosy Control Programme of 2009. The methods evaluated were Rapid Village Survey (RVS), Household Contact Examination (HCE) and Traditional Healers incentive method (TH). Effectiveness was measured as number of new leprosy cases detected and cost-effectiveness was expressed as cost per case detected. Costs were measured from both providers' and patients' perspectives. Additional costs and effects of each method were estimated by comparing each method against routine practise and expressed as incremental cost-effectiveness ratio (ICER). All costs were converted to the U.S. dollar at the 2010 exchange rate. Univariate sensitivity analysis was used to evaluate uncertainties around the ICER.

### Introduction

Leprosy is a communicable disease caused by a bacillus, Mycobacterium Leprae, which can lead to permanent disability among sufferers with significant psychosocial and economic burden. The disease causes skin lesions and nerve damages which progress to deformities of the eyes, hands and feet [1][2]. These physical disabilities are the prominent features of the disease which impose stigmatisation and discrimination on the sufferers [3]. The negative impact of leprosy due to stigmatisation is more than most other infectious diseases, making sufferers with physical disability dread stigmatisation and discrimination by the society [4].

In recognition of the burden of leprosy the World Health Organisation (WHO) in 1991 set a goal to eliminate the disease by 2000, defined as reducing the prevalence to less than one case per 10,000 populations [5]. Key targets of strategy for the reduction of burden of leprosy are the timely detection of new cases and prompt treatment with Multi Drug Therapy (MDT), which is the standard treatment for leprosy [6]. Since the progression of leprosy prognosis is insidious, taking an average of 2–5 years to manifest due to slow growth and multiplication of M. Leprae, early identification of the disease is very critical for effective control. This reduces both transmission of M. leprae and prevents disability.

Nigeria achieved WHO global leprosy elimination target of less than 1 case per 10,000 in 1998, but the country remains among those that still report relatively high number of registered leprosy cases [7]. According to the NTBLCP Annual Report 2009, implementation of MDT in the country as the strategic intervention to eliminate leprosy resulted to a rapid decline of registered cases from approximately 200,000 in 1989 to 6,906 in 2008 [7]. Disability Grade 2 (DG2) among the new cases were 14% while child proportion was 12%. The National Strategic Plan for Tuberculosis and Leprosy Control in Nigeria [8] is in line with the WHO's Enhancing Global Strategy for Further Reducing Disease Burden Due to Leprosy 2011–2015 [9]. The plan set the goal for reducing DG2 cases by 35% from 2010 figures by the end of 2015. Objectives include timely case finding and treatment, monitoring and limiting the progress of DG2 to not more than 5% annually. The plan recommends cost-effective approach to leprosy control interventions to ensure achievement of set goals. Several measures have been in place to control the disease in Nigeria, with support from international agencies such as the Netherlands Leprosy Relief (NLR) agency and other International Federation against Leprosy (ILEP) members. However the fact that indicators such as child cases remain high at 10% while DG2 stay at 14%, higher than target [7], [8], raises concern about hidden cases and continuous spread of the disease as well as the effectiveness of current detection methods in identifying early cases. This calls for the review of various detection methods to ensure more effective control of the disease in the region. Existing strategies include the routine/passive case detection (PCD), active case finding through the mini Leprosy Elimination Campaign (Mini- LEC) and contact examination.

Published studies suggest that effectiveness of different detection methods vary between settings and contact levels. For instance the effectiveness of HCE varies between countries and this tends to depend on leprosy endemicity and definition of ‘contact’. In high endemic communities in Indonesia, it was found that almost 80% of new cases could be defined as contacts [10]. In Orissa 72 additional cases could be detected through HCE of 400 index cases [11] in higher endemic areas, although in Bangladesh spatial clustering of new patients at household levels could not be clearly established [12], while in low endemic areas relatively higher proportions of new cases could be found among household contacts of index cases [13]. The RVS strategy has played important roles in India, Indonesia, China and Thailand [14], [15], [16], [17]. As part of the mini-LEC in Indonesia, it detected twice higher leprosy prevalence than routine programme activities [15]. It is known to detect cases early which mean shorter treatment for PB cases and less number of disabilities and leprosy reactions. Evidence of Traditional healers' contribution to leprosy case detection has also been documented [18]. They have gained the confidence of the community given their level of successes and affordable costs of treatment. Due to stigmatisation status of leprosy many suspected carriers would rather visit traditional healers for privacy than public health facilities or programmes. Hence, the need to collaborate with recognised practitioners to improve identification of leprosy cases in the community.

The objective of this study was to establish the cost-effectiveness of the three alternative leprosy case detection strategies in comparison to current practice with the aim to identify more efficient method for achieving the goals of the national programme in limiting child proportion and disability grade 2 cases.

### Methods

#### Study area and population

The study was conducted in Adamawa and Gombe states, two neighbouring north-eastern states of Nigeria with a combined population of over 5.8 million people in 2009, based on the 2006 population projection. The people are subsistent farmers and nearly 50% of the population are below 15 years old. There are over 1905 health facilities which include 2 Federal Medical Centers, 1 dermatology hospital, (which serves as a Leprosy referral center in the area), 1 specialist hospital, 15 general hospitals, and over I100 primary health centers (PHCs). Only about 11% (195) of the health facilities are private while the rest are public. 127 facilities provide leprosy services in Adamawa state while the dermatology hospital serves as the referral center. In line with national guideline Leprosy services are combined with Tuberculosis as National Tuberculosis and Leprosy Control Programme (NTBLCP) established in 1988. Both services are supported by the Netherland Leprosy Relief agency.

Although leprosy prevalence rate in the area in 2009 was similar to the national rate of less than 0.5 case per 10,000 population there exists the presence of high and low endemic communities. Eight of the 32 Local Government Areas (LGA) making up the study states registered prevalence rates of more than 1 case per 10,000 population in 2009 [19], similar to new case detection rate (registered incidence). The two states have DG2 cases and child proportion higher than the national targets of 5% among new cases [8]. In Gombe state alone child proportion was 13.4% in the same period [19] indicating possible active transmission of leprosy in these communities.

#### Study design

A cross-sectional study was designed across the high- and low-endemic communities of the states to evaluate a one year operational cost-effectiveness of the different case detection methods based on retrospective data available from 2005. The communities represented by the 32 LGAs were first categorised as either high-endemic or low-endemic using prevalence data from the NTBLCP 2009. Communities with registered prevalence rate of more than 1 case per10,000 population were categorised as high-endemic while those with less than 1 case per 10,000 population were categorised as low-endemic. Five communities were randomly selected from each endemic area. The ten sampled communities have a combined population of about 2,036,400. Selection was carried out to ensure geographical balance across the study area. Other criteria for selection were access to clinics providing MDT services for confirmed leprosy cases, data availability and comparable socio-economic status. Data was collected between 2005 and 2011. Effectiveness was measured as the number of new cases detected over a one year period and outcome expressed as cost per case detected.

#### Intervention strategies assessed

Case detection or finding methods are categorised as passive and active methods. The passive case detection method, which constitutes routine practice in this study generally involves voluntary or self reporting by patients with suspected cases, and the active case finding methods at which health personnel visit patients at homes (contact tracing) or vicinities. Each of the detection strategies was implemented as a complement to routine method. The following methods were evaluated and compared.

#### Passive case detection (PCD)

This represents the routine leprosy case detection method which integrates leprosy detection and control into the general health care system. It involves self-referral or referral of suspected cases by local health workers to leprosy units or peripheral health centre for examination by specialised health workers. The method involves the engagement of healthcare workers for the provision of leprosy services, regular staff training and supervision by state and local government Tuberculosis and Leprosy Staff (LGTBLS and STBLS), visits to health facilities (voluntary reporting) by patients, social mobilisation and health education.

#### Household Contact Examination (HCE)

For our study contacts of index cases who share the same house and a kitchen are examined, and does not include neighbours and social contacts. It is characterised by the following activities;

• One-day orientation for health workers on contact examination

### Discussion

This cost-effectiveness study is the first of its kind in leprosy control studies as no report of this nature, to our knowledge has been documented in the recent past. The study was an operational cost-effectiveness analysis of leprosy case detection methods (in routine practice), relying mainly on retrospective data between 2005 and 2011. It is based on integration of each strategy with routine method to complement and improve existing practice in detection of new leprosy cases. The study indicated that HCE, in its present definition is the most cost-effective alternative in detecting new leprosy cases in the study area, generating $142 per additional case detected in relation to routine practice alone. The robustness of this finding was evidenced in all contact levels and from both providers' as well as patients/family perspectives which showed similar results. The perspectives of the study were necessary to analyse the costs and benefits data from broader viewpoints that include the patients/family for a more balanced and comprehensive decisions, such as considering the need for subsidy. Comparative effectiveness within the study period suggested that the active detection methods were more effective at detecting DG2 cases than the passive routine method, with the THs strategy having the highest proportion of DG2 among the new cases. This is not surprising since due to stigma associated with leprosy the patients are less likely to present at public health facilities. Poor access to public health facilities may also contribute to low case detection rate in the routine method. Since no study has been documented on the cost-effectiveness of case detection methods, it was not possible to make comparisons. Published studies on cost-effectiveness analysis of leprosy interventions are very limited [4], and none is related to case detection, making comparison of study findings difficult. At$142 per additional case detected, it compares favourably with other leprosy interventions. A study in Bangladesh [24] evaluated the cost-effectiveness of chemo-prophylactic intervention with a single dose Rifampicin in household contacts of new leprosy patients, which resulted in a CER of $158 per additional case prevented. The study presented an interesting finding on the cost-effectiveness of chemoprophylaxis with rifampicin, implemented in conjunction with HCE. It demonstrated greater cost-effectiveness of leprosy prevention. Although the addition of rifampicin represents a limited additional cost to the intervention, it added significantly to the effect of the HCE. Applying this approach to the HCE as a routine strategy in the Nigerian context will further reinforce the cost-effectiveness of the strategy in leprosy case detection. The CER falls within the WHO's category of studies classified as highly cost-effective interventions, being less than three times the Gross Domestic Product (GDP).The low unit cost per case detected at$193 indicates that resource use is lower or more efficient in detection of more cases, suggesting that it will be easier to scale-up to achieve increased case detection rates to enhance elimination of leprosy.

The study justifies the use of HCE as a routine method in many countries in line with WHO recommendation [11]. Many factors can explain the findings, such as implementation costs which was the lowest per unit of output (per case detected). Leveraging on existing health care facility, the method requires less manpower. Results of sensitivity analysis reinforce HCE as the most cost-effective method in the study area, providing insight into the likely changes in the study findings in other settings, further reinforcing the findings. However it is noteworthy that the cost-effectiveness of the THs strategy is close to the HCE in all cases. The method also detected most DG2 cases compared to other strategies and this is instructive for achieving the objective of reducing the DG2 incidence as a major focus of the National Strategic Plan. This suggests that implementation of the THs strategy in combination with HCE, especially in areas where it was found to be most cost-effective will maximise case detection and help identify more of the DG2 cases. Similarly the RVS was found to be most cost-effective in Adamawa state and reducing the leprosy proportion of shared cost increased the overall cost-effectiveness of the strategy. This suggests that smarter use of resources to reduce cost without compromising quality will increase the cost-effectiveness of the RVS and targeted combination of strategies will generally enhance the efficiency of the detection methods.

#### Limitations of the study

Interpretations of the result need to be carried out in relation to some limitations of the study which is important for generalising the findings. Based on retrospective data from routine practice, it is subject to recall biases. Resource use data were not very detailed and specific, resulting in greater efforts at separating and allocating resources which, in many cases were arbitrary. The gap in data availability may have resulted in some costs not adequately captured. Hence cost allocations may not be very appropriate and accurate requiring the need for field implementation to obtain more accurate results, by correcting identified challenges. This was general for all methods.

Diagnostic accuracy was also not very specific as separation of cases between the PCD and RVS methods was in some cases challenging due to poor data documentation, which again would be addressed in a field study. Analysis of effectiveness data did not consider future impact beyond a one year period as the mix of leprosy cases detected have varying benefits from preventing the progression to permanent disability. The higher the number of early disease cases the greater the potential benefits of being prevented from progression to permanent disability, with MDT treatment. The use of DALY as a measure of outcome will involve the measure of utility for each leprosy grade detected such that the higher the number of early cases the higher the utility and hence the benefits. Lack of data on utility values and inadequate information on the proportion or distribution of leprosy categories limited this approach. However this may not have changed the study findings since the methods yielded similar proportions of child and DG cases. Definition of HCE in the study was the narrowest, limiting contact of index cases to household members, excluding neighbours and neighbours of neighbours which have been shown to increase case detection [23], [24]. Hence broader definition of contact tracing would increase the cost-effectiveness of HCE. Lastly given the dynamic nature of leprosy transmission as a communicable disease, the study did not capture the benefits of prevention beyond one year, but was only based on analysis of primary prevention. A dynamic model would have captured the benefits of further prevention beyond the index cases but this was not possible as information on the long term impact of prevention is not available. This would also have increased the cost-effectiveness of the various methods, especially for HCE.

In addition to the study limitations it would also be necessary to consider other factors such as economic differences between countries when generalising the study results. Programme costs will likely differ due to varying price levels of items such as personnel salaries and allowances, etc, leading to possible variation in cost-effectiveness results.

#### Recommendations

In view of the findings from the study we make the following recommendations to enhance effective detection and control of leprosy in Nigeria.

1. The study findings suggest the need to carefully implement and integrate HCE into routine practice for more effective identification and control of leprosy in the area. Furthermore broadening the definition of contact tracing to include neighbours of neighbours would increase the rate of detection, since the cost-effectiveness in the study was achieved at the narrowest definition of contact tracing. With established benefits with chemoprophylactic combination with rifampicin, the cost-effectiveness of the HCE would be further enhanced.
2. The lower cost of implementation of the HCE which generated the lowest average cost per case detected (ACER) offers the best option for scale-up to increase coverage and the detection of more leprosy cases.
3. The Traditional Healers incentive method demonstrated value close to the HCE as the next most cost-effective strategy. This suggests the need for a combination of the two strategies for a more comprehensive case detection, to cover potential cases that often rely on traditional healers for healthcare service, and enhance elimination of leprosy. It is also possible to implement the RVS method as part of the integration, in areas where it was most cost-effective. These combinations would maximise the benefits of each method without affecting the budget.
4. In recognition of the many limitations of the study related to data collection due to the retrospective perspective of routine practice, it would be best to carry out implementation studies in the field to correct data gaps and improve accuracy and reliability of study findings.

#### Conclusion

The study has shown that the Household Contact Examination is the most cost-effective approach for identifying new leprosy cases when implemented to complement routine practice in Nigeria. It offers the best option for scale-up for improved coverage having the lowest average cost per case detected. Broadening the definition of contact tracing will enhance detection of more leprosy cases for improved control. The combination of HCE with chemoprophylaxis would further enhance the cost-effectiveness of the intervention. Integration of the strategy into routine practice is therefore recommended for improved case detection of leprosy in Nigeria, depending on its acceptability and feasibility in the area. The finding also justifies the WHO recommendation for inclusion of contact tracing into routine case detection. However due to challenges in data collection (and generally in cost-effectiveness studies), large differences in results make more sense than the little differences recorded in this study. Hence the cost-effectiveness of the three methods can be considered similar and implementation of the methods in a budget neutral way may be necessary to maximise the detection of leprosy in the area, targeting specific areas where each method is considered more effective.

### Author Contributions

Conceived and designed the experiments: CE EP OO. Performed the experiments: CE SJ AS. Analyzed the data: CE EP AN OO. Contributed reagents/materials/analysis tools: CE EP SJ OO AS AN. Wrote the paper: CE.

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