Setting
This study was carried out in Chitwan district in central Nepal, where some mental health services were already in existence at the time of study, as described previously.28,29 In previous studies, approximately 41% of people reported symptoms of depression in the north-western mountains,30 compared to 3% in this sample from the central plains31, of whom only 8.1% accessed treatment.31 Despite Chitwan having adopted the National Mental Health Policy in 1996, there were only 2 psychiatrists serving its population of over half a million32 at the time of the study.
Sampling and participants
The rationale, study design and data collection procedures for the PRIME study have been detailed previously.31 Briefly, the PRIME study included a population-based survey of adults in Chitwan District. Using household and population data from Village Development Committees (VDCs; similar to municipalities, with community participation in their administration) in Chitwan, the lead investigator randomly selected houses from each VDC, where field workers enumerated the adults in the household and a family member randomly selected 1 adult from a series of concealed papers for recruitment into the study. Eligibility criteria included age of 18 years or over, residency in Chitwan, fluency in the Nepali language and willingness and ability to provide informed consent. Between May and August 2013, 99% of eligible adults provided informed consent and 2040 adults participated in the study.
All PRIME participants answered questions about demographic characteristics and received screening for probable depression (described below) and alcohol-use disorder in Part 1 of a two-part survey. To facilitate the analysis of secondary research questions without overburdening research staff and participants, questions about household economic status, healthcare utilization and OOP expenditure were included in Part 2 of the survey (also described below), which was limited to a sub-sample of 479 participants. This sub-sample included all participants reporting symptoms of depression (acute or chronic) (213), alcohol-use disorder (78) or both (18) and a random 10% sample of remaining screen negative participants (170) as shown in Additional File 1. The decision to include 10% of remaining participants was based on an estimated 10% prevalence of alcohol use disorder or depression, thereby enabling comparisons of equal numbers of screen positive and screen negative participants.
The questionnaire was orally administered by a trained fieldworker in the Nepali language and responses were collected on a questionnaire application, which was programmed onto an Android mobile device.
Measures
Depression status
We screened participants for depression with the 9-item Patient Health Questionnaire (PHQ-9)33. The PHQ-9 grades self-reported symptoms of depression in the previous 2 weeks and severity is determined by increasing scores. We interpreted a score of 10 or more to reflect probable depression, which in a Nepali validation study had a sensitivity of 0.94 and specificity of 0.80.34 In this sample, the PHQ-9 had a Cronbach’s alpha of 0.79.31
Household Economic Status
Household economic status was evaluated on the basis of household assets (such as water supply, sanitation facilities, power supply, radios, televisions, mobile phones, cooking fuel, a separate kitchen and type of flooring) using an asset score, which was developed specifically for use in Nepal for the purposes of this study and described further in Additional File 2. Employing the methods described by Vyas and Kumaranayake35, we used principal component analysis to generate a relative wealth index from the asset score, which we subsequently categorized into thirds to reflect low, average and high wealth categories.
Healthcare utilization
We assessed inpatient and outpatient healthcare utilization and OOP healthcare expenditure using a version of the Client Socio-demographic and Service Receipt Inventory36, which has been adapted for use in LMIC.37 To measure inpatient healthcare utilization, we asked participants to report the number of times they had been admitted to hospital in the previous 12 months, if at all. We then asked participants to report the number of times, if any, they had visited outpatient services for any health problem (including but not exclusively for depression) over the previous 3 months including seven types of healthcare providers: traditional healers, community workers, nurse/midwives, pharmacists, general doctors, specialist doctors, and psychiatrists and other mental health workers. In order to make comparisons between inpatient and outpatient healthcare utilization and to calculate an estimate of total utilization, we standardized the number of visits in 3 months to reflect annual outpatient healthcare utilization as reported in similar analyses.10,17,38 We also recorded data on the presenting health complaint.
Healthcare expenditure
For each inpatient hospital admission reported in the past 12 months, we asked participants to report all individual payments for hospital fees, medicines, laboratory tests and other investigations (including scans), and transportation incurred both personally and by friends and family. We used the sum of all these payments to estimate the annual inpatient OOP expenditure. The inclusion of payments for transportation to and from health facilities in the definition of OOP expenditures is consistent with other OOP cost studies from LMIC.39
For each episode of outpatient healthcare utilization over 3 months, we also asked participants to report all individual OOP payments for consultations with western biomedical practitioners or providers of traditional and complementary medicine as well as return transportation. We also standardised these payments to reflect annual outpatient OOP expenditure. Finally, we summed the annual inpatient and outpatient OOP expenditures to estimate the total annual OOP expenditure. We did not include opportunity costs or indirect costs such as lost productivity and all costs were defined from the user’s perspective. All expenditures were reported in Nepali Rupees and converted to US dollars according to the exchange rate at the end of data collection (1 USD:96.997 Nepali rupee on 02 Aug 2013). We observed one implausible outlier for outpatient OOP expenditure and replaced it with the sample’s mean outpatient OOP cost.
Statistical analysis
First, we report participants’ demographic40 characteristics, PHQ-9 scores, frequency of healthcare utilization and mean OOP expenditures, stratified by depression screening status. Categorical measures are summarised as proportions, as means and standard deviations and PHQ-9 scores and healthcare utilization (whose distribution was skewed), as medians and interquartile ranges. We present mean annual OOP expenditures, overall and by depression screening status, employing bootstrapping methods with 1000 replications to estimate standard errors. This method enables estimation of mean expenditures required for health budgeting41, whilst accounting for the skewed distribution typical of cost data42,43 and has been used with survey data of this nature previously.44 One participant who had missing age was imputed to 39.8 years, the mean value for the overall sample. Second, we assessed the relative changes in annual inpatient, outpatient and total healthcare utilization (by number of visits) for each unit increase in PHQ-9 score in all participants. Given the skew in the distribution of healthcare utilization, which precluded use of linear regression, we used negative binomial regression. Third, we estimated the relative changes in inpatient, outpatient and total OOP healthcare expenditure for each unit increase in PHQ-9 score using bootstrapped linear regression models. We adjusted for age, sex and relative wealth index in all models. We used the relative wealth index as a proxy for household economic status and specifically for access to basic necessities, which has been shown in Nepal to predict healthcare utilization.15 In exploratory analyses, we also adjusted for education and occupation as potential confounders of the association between depression and healthcare utilization but omitted these from the primary model to avoid collinearity. We also checked for interactions between PHQ-9 score and relative wealth group. Finally, we report utilization and mean OOP expenditures for each outpatient provider type, stratified by probable depression status.
For each step, survey-adjusted methods were used to account for the complex sampling design and sampling probability weights.45 Data were analysed using Stata version 14.2.40 Ethical approval was obtained from the Nepal Health Research Council (Kathmandu, Nepal), the World Health Organization (Geneva, Switzerland) and the London School of Hygiene and Tropical Medicine.