Cost analysis of outpatient services for major external structural birth defects: An ingredient approach in selected hospitals in Kiambu County, Kenya [version 1; peer review: awaiting peer review]

Background: Major external structural birth defects are known to exert an enormous economic burden on individuals and health services; however, they have been vastly unappreciated and underprioritized as a public health problem in settings where cost analyses are limited. Objective: The objective of this study was to conduct a cost analysis of outpatient services for major external structural birth defects in selected hospitals in Kiambu County, Kenya. Methods: A hospital-based cross-sectional study design was adopted in four hospitals where an ingredient approach was used to retrospectively gather data on cost drivers for interventions consisting of  castings, bracings, and tendonectomies for the under-fives from health care providers’ perspectives for a one-year time horizon (January 1st, 2018, to December 31st, 2018). The hospitals were selected for providing outpatient corrective and rehabilitative services to the under-fives. Prevalence-based morbidity data were extracted from outpatient occupational therapy clinic registers, whereas stafftime for the hospitals’ executives comprising the medical superintendents, chief nursing officers, orthopedic surgeons, and health administrative officers were gathered through face-to-face enquires from the occupational therapists being the closest proxies for the officers. Following a predefined inclusion criterion, 349 cases were determined, and associated cost drivers identified, measured, and valued (quantified) using prevailing market prices. The costs were categorized as recurrent, and unit economic costs calculated as average costs, expressed in U.S Dollars, and inflated to the U.S Dollar Consumer Price Index from January 2018 to December 2018. Results: The unit economic cost of all the cases was estimated at $1,139.73; and $1,143.51 for neural tube defects, $1,143.05 for congenital talipes equinovarus, and $1,109.81 for congenital pes planus. Conclusions: The highest economic burden of major external structural birth Open Peer Review Reviewer Status AWAITING PEER REVIEW Any reports and responses or comments on the article can be found at the end of the article. Page 1 of 13 F1000Research 2021, 10:359 Last updated: 10 MAY 2021


Introduction
Major external structural birth defects (MESBDs) are defined as physical abnormalities of intrauterine origin present from birth, detectable visually, and having significant health and development impacts [1][2][3][4] . These defects are potentially fatal and those children who survive beyond infancy require substantial economic resources to deal with lifelong disabilities [5][6][7][8][9] . Worldwide, approximately 134 million births reportedly occur yearly, of which 7.9 million (6%) are born with at least a major birth defect, mostly affecting the central and musculoskeletal systems [1][2][3][4]10 . Although about 3.3 million of these children die before they are five years old, the 3.2 million who survive may be disabled for life if sufficient resources are not dedicated to corrective and rehabilitative health services 1,2,8 .
MESBDs continue to occur exerting an enormous economic burden on individuals and health services in developing countries; however, they have been vastly ignored and unappreciated as public health problems due to limited estimation of the associated costs attributed to the scantiness of, and inaccurately profiled data on cost drivers 1,2,9,11 . Even though these defects remain a "silent" global public health problem, the highestburden is shouldered by developing countries due to high prevalence of modifiable risk factors coupled with deficient expertise in economic evaluation studies [1][2][3][4]6,8,9,[12][13][14][15] . Hospital charges for new-born children born with some forms of birth defect have been reported as four to eight times higher than those without any form of the defects 16 . Cost analysis is a partial economic method of evaluating health care programs used to compare the costs of at least two alternative interventions; however, cost studies are still useful even in the absence of comparative interventions as they can establish baseline economic costs of a health intervention [17][18][19] .
Children surviving beyond infancy could require restorative health services to reduce the adverse impacts associated with MESBDs 1,2 . These interventions are described as corrective and rehabilitative outpatient services consisting of castings, bracings, and tendonectomies whose monetary value is referred to as economic or opportunity costs 17,18,[20][21][22][23][24] . The resources used in the provision of such services could be quantified through micro-costing (bottom-up) using an ingredient approach to gather data on the cost drivers by a step-down full costing technique, activity-based costing, time and motion, surveys, and manager interview techniques 17,18,20,[25][26][27] . Alternatively, these inputs may be quantified by gross costing (top-down) using historical input outlay 17,18,20,[25][26][27] .
The range, contexts, and extents of cost elements are determined by economic viewpoints consisting of health care providers', individuals', or societal perspectives that are informed by policy decisions known as the study objectives, and/or questions 17,18,20,26 . The existing market prices and opportunity costs (forgone benefits) are used to value the inputs in the monetary units categorized as recurrent and capital costs 17,18,[20][21][22][23][24] . These costs are assigned to direct, indirect, and intermediate cost centers using a step-down accounting technique 17,18,[20][21][22][23][24] . The costs of the inputs are sometimes shared among the cost centers thus referred to as overhead (shared or joint) costs which are proportionally allocated to the respective cost centers for estimating final economic costs 17,18 . Capital costs determined for more than a one-year time horizon should be considered for the differentialtime discounting unlike recurrent costs 17,18,[20][21][22][23][24] . Similarly, statistical and/or sensitivity analysis should be conducted to ascertain the robustness of the evaluation findings because of potential uncertainties arising from sample size determination and data collection methods for the cost drivers 17 .
The advancements in medical and surgical interventions are known to reduce the severity of lifelong physical disabilities related to MESBDs; however, their costs are catastrophic and prohibitive to many households and public health care systems globally 1,2,9,15 . Even though substantial resources are usually allocated to health care systems for the provision of corrective and rehabilitative health services for MESBDs, their costs are seldom estimated due to the rarity and stochasticity of the defects, scantiness of the cost data, inaccurately profiled cost information and inadequate costing expertise in developing countries 19,20,28,29 . The scarcity of local epidemiological data and differences in the epidemiological study design (prevalence/incidence-based) also impede the accuracy of the profiled cost data in developing countries 19,20,28,29 .
Economic costs increase the extent to which health services, individuals, and society are affected by MESBDs because of the forgone benefits of not investing in the next best alternative [16][17][18][20][21][22][23][24]30 . Corrective and rehabilitative health care services for MESBDs is critical in reducing the severity of lifelong disabilities and improving the quality of life for the affected children, as well as the economic productivity of the affected families 1,2,9 . Thus, cost analysis is of public health importance in influencing and informing health planning, policy decisions, resource allocations, informing further economic evaluations and assessing health system performance 17,18,20,22,23,31,32 . Consequently, the objective of this study was to conduct a cost analysis of the outpatient services for MESBDs from the providers' viewpoints using an ingredient approach in selected hospitals in Kiambu County, Kenya.

Study settings, and designs
The study was conducted in four hospitals consisting of three county referral hospitals (Kiambu, Thika, and Gatundu), and PCEA Kikuyu orthopedic (faith-based) selected for providing corrective and rehabilitative outpatient health services to children born with MESBDs in the county. The three county referral hospitals were purposively selected being the only public hospitals providing these services in the county, whereas PCEA Kikuyu orthopedic hospital (faith-based) was selected by simple randomization using sealed envelopes between two faith-based hospitals for providing the same services in the county. A hospital-based cross-sectional study design was adopted to generate cost data from prevalence-based local morbidity data gathered using an ingredient approach to estimate the economic costs of corrective and rehabilitative outpatient health services from health care providers' perspectives. This was however the best choice of study design for measuring the unit economic cost of health services as an attribute of the population, and thus provided a snapshot of the burden associated with the 'silent' public health problem and allowed for generalization of the study results in similar hospital settings in the region. Even though incidence data were readily available and easily accessible for the costing activity, prevalence-based data were excessively preferred to improve the accuracy of the profiled cost data and the estimation of the unit economic costs. This was an economic evaluation study, therefore was reported as per the CHEERS (checklist for consolidated health economic evaluation reporting standards) guidelines 27 .

Study population and eligibility for participation
The study population consisted of all children aged under five years old born to resident women of Kiambu County between January 1 st , 2014, and December 31 st , 2018, Cases were defined as live births with at least one clinically obvious major external structural birth defect referenced/or described by assistant occupational therapists and/or orthopedic surgeons and presented to the occupational therapy clinics for care from January 1 st , 2018, to December 31 st , 2018. Caregivers of children born with MESBDs were likely to seek outpatient corrective and rehabilitative health services at the study hospitals whether the children were born in or out of the county. Thus, the eligibility criterion defined above could minimize systemic bias and ensure the reliability of the study results.
Study perspective, time horizon, and discount rate The data for cost drivers were gathered retrospectively from health care providers' perspective for a one-year time horizon between January 1 st , 2018, and December 31 st , 2018 for purposes of maintaining similar currency conversion, and inflation rates. Discounting for differential timing did not suffice in this study because the value of the resources considered for the analysis were categorized only as current costs.
Unit economic costs, currency conversion, and study assumption The total (annual) economic costs were calculated for the defects (349 cases) for computing the unit economic costs as an average of the total costs expressed in Kenya Shillings (KES). The unit economic costs were calculated by dividing by the total annual costs by the number of cases using the following formula: -

Data collection process
Before data collection began, the Principal Investigator (PI) recruited and trained four nursing graduates as research assistants (RAs) to ensure that the data abstraction process that spanned from August 1 st , 2019 to September 30 th , 2019 was carried out in a standardized manner. We adopted an ingredient approach to retrospectively gather the prevalence-based data on caseloads for the cost analysis of corrective and rehabilitative outpatient health services. The cost ingredients of bracing, tendonectomy, and casting interventions quantified consisted of caseloads (morbidity data) by type of MESBDs, the number of braces, the number of bracings, the number of bracing review visits, the number of casting materials, the number of castings, the number of casting review visits, the number of tendonectomies, and the number of tendonectomies review visits considered as direct recurrent costs; and staff emoluments, staff-time, building space for rental, and utility charges categorized as overhead recurrent costs. The prevalence-based morbidity data were retrospectively drawn from outpatient occupational therapist registers; described as medical records containing information on health services provided to children with major external structural birth defects. The information captured in these registers includes dates of clinic visits, outpatient numbers, names of the patients, patients' age, residence, diagnoses, and therapeutic interventions, among others. Following a predefined inclusion criterion, 349 cases were determined, and associated cost drivers identified, measured, and valued (quantified) using prevailing market prices and entered in a predetermined secondary data abstraction tool. On the other hand, staff-time for the hospitals' executives comprising the medical superintendents, chief nursing officers, orthopedic surgeons, and health administrative officers were gathered through face-to-face enquires from the occupational therapists being the closest proxies for the officers mentioned above. The ingredient technique and prevalence-based data were chosen for possibly of generating detailed and improved accuracy of the profiled costing data. The data gathered comprised the following: -Caseloads/morbidity data: Following a predefined exclusion criterion, 349 cases of MESBDs were considered for the cost analyses.
Casting: Castings used to stabilize the affected feet consisted of Plaster of Paris (POP) bandages, orthopedic cotton bandages, and glycerine valued at local market prices. A set of these materials valued at $3.9 were used to cast two cases of club foot. The study computed the number of castings and the number of revisits after the procedure for all cases of CTEV treated using these strategies.
Braces: Braces consisted of leather foot covers, rubber soles, and metallic rods used to stabilize cases of club foot. Braces were sourced from the local markets as ready-made products, therefore, were valued at $15.31 using prevailing market prices. The study also enumerated the number of braces and the number of revisits after the procedure for all cases of CTEV treated using this strategy.

The number of tendonectomies:
This was a procedure performed by surgeons to extend the Achilles tendon in club feet. This is largely an outpatient specialized procedure, therefore, existing market hospital charges for outpatient specialized surgical procedures were used to value the cost of tendonectomies estimated at $51.02. Similarly, the number of tendonectomies and the number of revisits after the procedure were computed for all the cases of CTEV that adopted this treatment strategy.
Emolument for personnel: The personnel comprised assistant occupational therapists and support staff whose emolument were estimated based on the respective schemes for staff with at least ten years of work experience 34-36 . Emoluments for assistant occupational therapist consisted of basic salary, house allowance, commuter allowance, health risk allowance, and health extraneous allowance, whereas, for the support staff comprised basic salary, house allowance, and commuter allowance 34-36 . The monthly salary and benefits for an assistant occupational therapist at "Grade 10'' was valued at $1,224.50, whereas support staff at "Grade 14'' was valued at $173.50.
Renting building space: Occupational therapy outpatient clinics were identified within the respective study hospitals whose plinth floor surface areas were measured in square feet and valued based on the existing local market rates for renting building spaces. The total renting space for the four hospitals was estimated at 3,593.63 square feet and valued at $0.37 local market value. Patient consent for publication: Patients were not directly involved because data was drawn from the medical registers, thus consent was not required.

Minimization of biases
Case ascertainment, information, and systemic biases were expected in this study; therefore, the PI began by predefining an eligibility criterion (case definitions) for participation in the study and predetermining a secondary data abstraction tool for purposes of reducing case ascertainment biases. On the other hand, information biases were reduced by training the data collectors on secondary data extraction techniques from the outpatient occupational therapy clinics and entering data into the abstraction tools to ensure the process was conducted in a standardized manner. Further, all the registers for the entire one-year study period (2018) were reviewed and listed all the cases of external structural birth defects to reduce ascertainment and information biases in this study. Systemic bias was also reduced by excluding cases of delayed milestones, and/ or developmental conditions due to management intervention similarities.
Data processing and statistical analysis Capital costs did not suffice in this cost study because movable, and fixed capital resources were not considered for valuation because no inventory records existed for furniture, examination couches even though they appeared to have lost more than half of their economic half-lives, and capital donations in kind, whereas motor vehicles, motorcycles, and bicycles were not used either as direct, indirect, or intermediate costs for corrective and rehabilitative health services for the under-fives with MESBDs. The occupational therapy clinics on the other hand, also as fixed capital costs, were exceedingly small portions of the respective hospitals' floor plinths, hence valued as recurrent costs using prevailing local market prices for building space rental.
Inflation factor and statistical uncertainties: All the resources were categorized as recurrent costs and inflated to the U.S Dollar ($) Consumer Price Index (Calculator) for a oneyear time horizon from January 2018 to December 2018 33 . This computation adjusted the unit economic costs to purchasing power parity as a factor of inflation, and minimized statistical uncertainties due to cost data scantiness and collection methods 32,33 . Consumer Price Index measures the mean changes in market prices over some time in which consumers pay for goods and services such as health services for MESBDs, thus was preferred because of being the best optimal measure of inflation in this study 33 .

Estimation of unadjusted economic costs
The annual economic costs were estimated and adjusted for inflation factors using the consumer price index calculator (CPI). Of the total unadjusted annual cost for all cases of the observed MESBDs ($392,436.49), almost two-thirds (71.48%) of resource inputs were accounted for by emoluments of occupational therapists, whereas administrative staff-time accounted for about one-quarter (18%) ( Table 3).
Of the total unadjusted economic costs, overhead (shared) costs for these defects consisted of staff-time, staff emoluments, and utilities were estimated at $376,553.05 (Table 4). Of the    (Table 4).
Of the total unadjusted annual economic costs for major external structural birth defects; congenital talipes equinovarus was estimated at $343,959.87, whereas congenital pes planus and neural tube defects were estimated at $38,322.97 and $10,153.67, respectively ( Table 6).  (Table 7).

Estimation of adjusted economic costs:
The study showed relatively similar unit economic costs of the defects despite wide variations among the caseloads for specific types of MESBDs (Figure 1).

Discussion
To our knowledge, this was the first study to estimate the unit economic costs of MESBDs from health care providers' economic perspective among the under-five-year-old children in Kiambu County, Kenya. Substantial public health resources are continually allocated to the health care systems for care of children with MESBDs, however, the unit economic costs of care are barely known because they are rarely estimated mainly in the developing countries 9,29 . Sufficient access and utilization of corrective and rehabilitative health services remain an important public health intervention for improving the quality of life for birth defect-affected children globally [1][2][3][4] . Even though limited cost data, inadequate costing expertise, and the rarity of   Table 6. Resource inputs for the sub-groups of the defects.  Despite defects of the central nervous system contributing the least number (9) of cases compared to congenital talipes equinovarus (305), and congenital pes planus (35), its unit economic costs was relatively equivalent to the costs of the latter two types of the MESBDs observed in the county ( Figure 1). Although some forms of neural tube defects are potentially fatal, the children who survive beyond infancy require substantial economic resources to deal with the related adverse health impacts 1,2,9,15 . The results of this study were indeed consistent with other research findings in the region and across the world that the greatest burden of disease associated with MESBDs is usually accounted for by the defects of the central nervous system 11,15,37 . The economic burden of spina bifida is usually substantial throughout the life of the affected individuals ascribed to the experienced high medical care expenditures in the early years of life with the defect and later reduced milestone development usually associated with spina bifida 11,38 . Our study similarly showed that neural tube defects followed by congenital pes planus accounted for the highest disease burden associated with MESBDs being shouldered by the health care systems in Kiambu county.

Castings
Even though our study estimated the economic costs of these defects among the under-five-year-old children, our findings mimicked results of other studies such as in Germany where similarly high staggering economic costs were encountered among the general population with various forms of NTD   19 . Low undertakings of cost studies, particularly in low-and middle-income economies have been attributed to the scarcity of data on the burden of these defects, 20,28,29 . Thus, the variations of annual direct economic costs could have been due to differences in the availability of the cost data, costing expertise, health services access, and utilization (economies of scale) 5,17,19,39 . Despite variations observed in the estimates of the economic costs, these findings point to the continuous disease burden associated with MESBDs in the county underpinning efficiency in resource utilization, and allocation for MESBDs in public and faith-based health facilities.
The few cases of NTD observed in this study could be attributed to a proportion of the carers of children with NTD seeking alternative therapies due to the associated adverse psychosocial effects experienced by the affected families 38,[40][41][42] . Thus, the economic costs of NTD would be exponential compared to other forms of the defects observed in the study if all carers would have sought for care from the respective study hospitals.
Nevertheless, the estimated costs demonstrated the potential catastrophic burden of the 'silent' economic problem in the region, thus underscores more scientific efforts to understand the magnitude of MESBDs regionally 9 . The observations made by this study have contradicted the epidemiological and economic fallacy that MESBDs are not of public health priority relative to other health events especially in resource-constrained countries [1][2][3][4] . Nevertheless, some limitations were inherent in this study; first and foremost, medical records used to draw the cost data were not designed for economic evaluation studies, whereas some of the defects were likely to delay childhood milestone development prolonging the demand for corrective and rehabilitative outpatient service possibly leading to more economic expenditures. The researchers also experienced difficulties in distinguishing the extent of the cost drivers for congenital talipes equinovarus occurring with spina bifida, congenital talipes equinovarus occurring with germ valgus, and spina bifida occurring with hydrocephalus, potentially due to inaccuracies of the profiled cost data.

Conclusions
This study estimated the economic costs of outpatient corrective and rehabilitative health services for MESBDs in Kiambu County in Kenya. Despite the fewest caseloads for the NTD, the study showed that NTD was associated with the highest burden of disease followed by CPP in the county. Despite CTEV proportionally contributing the highest caseload for the defects, it essentially accounted for the lowest burden of the disease associated with MESBDs in the county. This observation thus points to adverse developmental, and psychosocial impacts among the affected children and their families who are not able to access corrective and rehabilitative services. Similarly, these findings suggest a possible reduced economic productivity among the affected families arising from direct and indirect costs associated with major external structural birth defects. Therefore we would like to recommend further studies on the direct and indirect economic costs of MESBDs among children of schoolgoing age to understand the impacts, and establishment of functional occupational therapy clinics in the ten sub-county hospitals to increase access of these services within Kiambu County.