Study sample
This study was part of a larger project with a published protocol [17].In a nutshell, four districts (or counties) were selected for field trial. One of the districts (Garmsar) was considered the no-intervention, and the other three were intervention districts. In each selected district, four urban and four rural CHCs were selected. In each of the 32 selected CHCs, a baseline survey was conducted on 30 − 70-year-old residents to understand the existing status of NCDs risk factors from June to September 2018 using a Farsi translation of adapted WHO stepwise approach to surveillance (STEPS) questionnaires [18]. Then, four different Intervention Packages were randomly assigned to selected urban or rural CHCs in the intervention districts. In effect, one urban and one rural CHCs in any of the intervention districts received the Intervention Packages A, one urban and one rural CHCs in the district received the Intervention Package B, and so on. The interventions period was 12 months, after which the second survey was conducted on the same age population in the 32 CHCs to assess the impacts of the interventions from September to November 2019 (Fig. 1). We used a random sample of the general population. The sampling method was similar in both surveys, but the selected participants were not necessarily the same. The NPHWs in each CHCs were responsible for planning and running the interventions in their catchment area, with or without extra help by the core team of research (by education, consultation on operation planning or paying for performance). Although the survey participants were expected to be among the target groups of the interventions, they were not necessarily the ones who received the intervention directly. This is similar to the real situation where interventions do not necessarily affect all the target population.
Based on the approved protocol, the trial was planned to continue for 24 months, with a third survey at the end of the study. However, to comply with the country’s COVID-19 social distancing protocols, the trial was terminated prematurely after 12 months of interventions.
The selected districts were Shahriar (population = 744,210), Dashtestan (population = 252,047), Damghan (population = 94,190), and Garmsar (population = 77,421) (Additional file 1). The districts’ populations are based on the 2016 census [19]. A simple randomization method was used to select four urban and four rural CHCs in each district and to assign the Intervention Packages to the selected CHCs. Detailed explanations on the inclusion criteria for the districts, CHCs, and participants were explained in the protocol [17]. NPHWs implemented the four interventions packages after receiving extensive training. Physicians were not the target group of this trial because they were undergoing a separate incentive payment scheme [20]. The CONSORT checklist can be found in Additional file 2[21].
Interventions
An Intervention Package included at least one of the following interventions.
First intervention (target-setting): Short-term targets (e.g., decrease in tobacco use and salt consumption) were set based on the preliminary results obtained from the baseline survey. NPHWs were entirely responsible for planning to achieve the targets. In the first intervention, meetings were held with the NPHWs and they were informed about the status of NCD behavioral risk factors in their catchment area population (based on the first survey) and the national goals (it is set until 2025) to control NCDs behavioral risk factors were explained to them (Reduce tobacco use by 30%, Reduce insufficient physical activity by 20%, Reduce average salt intake by 30%, Reduce the consumption of fruits and vegetables in insufficient servings by 30%).
Second intervention (evidence-based education): The main research team reviewed and prepared documents on the effect of the interventions on the prevention of NCDs risk factors. After approval, these documents were shared with NPHWs and health experts during 16-hour workshops. we trained NPHWs about the methods of selecting, planning and implementing cost-effective and feasible interventions in catchment areas of community health center using Disease Control Priorities volumes 3 [22, 23], and the WHO package of essential NCDs (PEN) [24].
Third intervention (operational planning): The research team coordinated with NPHWs and health experts to devise operational plans based on the priorities of each CHC during a 12-hour workshop at each district. Also, the team allocated a supportive budget for the devised operational plans.
Fourth intervention (performance-based financing or PBF): The pay-for-performance method of financing was implemented. The incentives were paid in accordance with the pre-defined targets and indices every three months. The indicators of performance were set based on the objectives of the national document for the prevention and control of NCDs and related risk factors in Iran [25]. The maximum amount of incentive payment was paid to NPHWs who met 62.50% (5 out of 8) to 100% (8 out of 8) of their targeted goals. The maximum monthly incentive amount was 10% of the average monthly salary to NPHWs in the studied districts, which was determined to be approximately 25 million Rial (or 232 USD at a 107,832 Rial/USD current exchange rate [26]) after interviewing the district’s provincial supervisors appointed by the Iranian MOHME. Therefore, the full monthly incentive payment was approximately 23 USD. NPHWs who did not meet their goals were paid proportionally less. Specifically, those who met 50.00% (4 out of 8) to 62.49% (4 out of 8 plus partially meeting other ones) of their goals received two-third of the full amount, approximately 15 USD monthly in the corresponding three-month assessment period. Those who met 25.00% (2 out of 8) to 49.99% (2 out of 8 plus partially meeting other ones) of their goals received one-third of the full amount, approximately 8 USD monthly. Those achieving less than 25% of their goal received no incentive payment. No payment was delayed because they were made directly to the NPHWs’ bank account by the research team immediately after each assessment.
Specifically, Intervention Package A included only the first intervention. Intervention Package B included the first two interventions. Intervention Package C included the first three interventions. Intervention Package D included all four interventions (Table 1). CHCs that received Intervention Packages A, B, C, and D are also called intervention groups A, B, C, and D in this study respectively. The no-intervention control group (Garmsar district) received none of the interventions.
Every two to four weeks, the implementation status of the interventions was reviewed and checked by the district and province supervisors selected by the research team. Also, reports and documents related to interventions were received by the research team every quarter.
Table 1
Assignment of interventions to CHCs inside each of the three treatment districts
Intervention Package
|
Intervention Groups: Selected CHCs
|
Intervention:
|
Target-Setting
|
Evidence-Based Education
|
Operational Planning
|
Performance-Based Financing
|
A
|
1 Rural, 1 Urban
|
Yes
|
No
|
No
|
No
|
B
|
1 Rural, 1 Urban
|
Yes
|
Yes
|
No
|
No
|
C
|
1 Rural, 1 Urban
|
Yes
|
Yes
|
Yes
|
No
|
D
|
1 Rural, 1 Urban
|
Yes
|
Yes
|
Yes
|
Yes
|
Statistical analysis
This study’s objective was to compare NCDs Behavioral risk factors before and after the interventions and identifying effective interventions. NCDs Behavioral risk factors analyzed in this study were zero-one indicators of insufficient physical activity, insufficient fruit consumption, insufficient vegetable consumption, high salt intake, and tobacco use.
Not meeting the WHO recommendations on physical activity Metabolic Equivalent of Task (MET) (less than 600 METs per week) was defined as insufficient physical activity [27]. The WHO’s recommendations were used to determine insufficient fruits (less than two medium fruits, such as two medium apples or half a cup of nuts, in the last 24 hours) and vegetable consumption (less than three cups of raw leafy vegetables or one and a half cups of cooked or chopped vegetables in the last 24 hours) as well [28–30]. A person was identified as high salt consumer if the person always or often added salt or salt additives to the food [31]. Current tobacco smoking was defined as the use of any smoked tobacco products, including cigarettes, cigars, pipes, or any other smoked tobacco products, on a daily, non-daily basis in the last 30 days [32].
The prevalence of each NCDs risk factor in the baseline and second surveys was calculated in populations assigned with each Intervention Package. Then, the difference in the prevalence rates between the two surveys was calculated. For the more formal analysis of the effect of the designed Intervention Packages, the difference-in-difference (DID) design was employed. The following equation shows the linear specification of the DID design:
Equation 1.
$${\text{Y}}_{\text{i}\text{c}\text{t}}={\alpha }+{\beta }{\text{I}\text{n}\text{t}\text{P}\text{a}\text{c}\text{k}\text{a}\text{g}\text{e}}_{\text{i}\text{c}}+{\gamma }{\text{P}\text{o}\text{s}\text{t}}_{\text{i}\text{t}}+{\rho }\left({\text{I}\text{n}\text{t}\text{P}\text{a}\text{c}\text{k}\text{a}\text{g}\text{e}}_{\text{i}\text{c}}\times {\text{P}\text{o}\text{s}\text{t}}_{\text{i}\text{t}}\right)+{\theta }{\text{C}\text{H}\text{C}}_{\text{i}\text{t}}+{\delta }{\text{X}}_{\text{i}\text{c}\text{t}}+{{\epsilon }}_{\text{i}\text{c}\text{t}}$$
where i indicates a surveyed individual, c indicated the community health center to which the individual is affiliated, and t indicates survey year. The dependent variable, Y, is a binary variable that indicates one of the NCDs risk factors for the individual. The variable IntPackage is a categorical variable with five values (0, 1, 2, 3, and 4) that indicates which Intervention Package (listed in Table 1) was assigned to the CHC that the individual receives health services from. The value zero was assigned to those in control (no intervention) group. The variable Post indicates the survey year. It takes the value of 0 if the individual was surveyed before the implementation of the interventions in 2018, 1 if surveyed after in 2019. The variable CHC is a health center indicator (1, 2, …, 32) as people subjected to a specific Intervention Package could be affiliated to different health centers. This variable accounts for the influence of all unobservable/unmeasurable CHC-specific confounders that might not change over the one-year period of this study (e.g., health care resources in the community, attitudes towards using modern medicine versus traditional practices, distance from the CHCs, and overall weather patterns). The variable X is a vector of socioeconomic factors including age, sex, marital status (in three categories: never married, married, divorced or widowed), education level (in four categories: illiterate or primary, secondary, high school, and some college), labor market status (in six categories: public wage and salary job, private wage and salary job, self-employed, homemaker, retired, and unemployed), health insurance status, and homeownership status. The coefficient of interest in this specification is ρ that shows the effect of Intervention Package i (versus no intervention, for example) among those surveyed after the intervention.
Given the binary nature of the outcome variables in this study, logistic models were used in fitting Eq. 1. Odds ratios were calculated, representing the change in the odds of the dependent variable being equal to 1 due to one unit change in either of the terms on the right-hand side of Eq. 1, a transforming the logistic model results in:
Equation 2.
$$\text{ln}\left(\frac{{\text{p}}_{{\text{Y}}_{\text{i}\text{c}\text{t}}}}{1-{\text{p}}_{{\text{Y}}_{\text{i}\text{c}\text{t}}}}\right)={\alpha }+{\beta }{\text{I}\text{n}\text{t}\text{P}\text{a}\text{c}\text{k}\text{a}\text{g}\text{e}}_{\text{i}\text{c}}+{\gamma }{\text{P}\text{o}\text{s}\text{t}}_{\text{i}\text{t}}+{\rho }\left({\text{I}\text{n}\text{t}\text{P}\text{a}\text{c}\text{k}\text{a}\text{g}\text{e}}_{\text{i}\text{c}}\times {\text{P}\text{o}\text{s}\text{t}}_{\text{i}\text{t}}\right)+{\theta }{\text{C}\text{H}\text{C}}_{\text{i}\text{t}}++ {\delta }{\text{X}}_{\text{i}\text{c}\text{t}}+{\text{ϵ}}_{\text{i}\text{c}\text{t}}$$
where p_(Y_ict ) is the probability of Y_ict = 1. To account for the possibility that the NCDs risk factors (the Ys) may not be independently distributed within the population covered by each community health center, hence the estimated standard error be artificially low, standard errors were clustered at the CHC level [33].
The Sampling weight assigned to a surveyed individual was the multiplication of two ratios. One was the individual’s corresponding district’s share of the same age group and sex in the country’s population. The considered age groups were 30 − 39, 40 − 49, 50 − 59, 60 − 70, and the shares for urban and rural areas were calculated separately. The second was the share of surveyed people of the same age group and sex in the individual’s corresponding CHC.
To assess the extent of any potential bias in the selection of CHCs and the assignment of Intervention Packages, the estimations were done with and without adjusting for a set of measured socioeconomic factors, represented by X. The statistical package used for analyses was STATA 14.0 (Stata, Inc, College Station, Texas).
This study has been approved by the national committee on ethics in medical research (code: IR.NIMAD.REC.1396.084) as well as our institutional review board (code: IR.IUMS.REC.1395.1057613). Written informed consent will be obtained from study participants.