Setting and location
The study was conducted in four rural districts of Mozambique. Two districts served as intervention (with the new delivery model); and two served as control (with standard delivery model). These districts were selected based on pragmatic criteria described elsewhere . All four districts are rural, with limited access to health services, and low health, social and economic indicators [7, 8].
An observational and cross-sectional study with cost-effectiveness analysis component was carried out using secondary data from the pilot study conducted between October and December 2015 .
Collection of cost data
The campaign costs were retrospectively collected from the providers’ perspective. The costs considered were related to training of personnel, allowances, LLINs warehouse storage, LLIN transportation vehicles rental, and materials production (pamphlets, coupons, stickers, etc).
These costs were aggregated into four categories: 1) micro-planning; 2) LLIN storage; 3) LLIN transport; 4) mobilization and training at district level, household registration, and LLIN distribution.
Costs were collected in Mozambican Metical (local currency) and United States Dollars (US$). In 2015, the exchange rate was: 1 US$ = 42.00 Meticais. No adjustment for inflation was undertaken since all cost were paid in 2015. No discount rate was applied since the temporal universe of analysis did not exceed one year.
Comparators: the two delivery models
Both delivery models are community-based. One delivery model allocates LLINs based on the assumption of one LLINs for every two persons in a household (intervention districts), and another the number of LLINs is allocated based on assumptions around households members sleeping patterns (control districts). A comprehensive description of the models is reported elsewhere [7, 8].
Measurement of effectiveness
Two endpoints were used to measure the effects of the campaign in the intervention and control districts: i) number of LLINs delivered; ii) households (HHs) achieving universal coverage (UC) target (one LLIN for every two persons). The number of HHs achieving UC was estimated according to the following steps:
- Step 1: percentage of HHs achieving UC - [70.8% (95% CI: 67.6–74.0) in the intervention districts, and 59.6% (95% CI: 56.2–63.0) in the control districts] ;
- Step 2: registered HHs multiplied the step 1 results (136,985 HHs were registered in the intervention districts, and 120,246 HHs were registered in the control districts ).
The following cost-effectiveness measures were calculated: i) average cost-effectiveness ratio (ACER) per LLIN delivery; ii) ACER per HH achieving UC; iii) incremental cost-effectiveness ratio (ICER); and iv) incremental net benefit (INB).
- The ACER per LLIN delivered and ACER per HH achieving UC was calculated by dividing the total implementation cost by the number of LLINs delivered and number of HHs achieving UC, respectively.
- The ICER (which indicates the additional amount of money needed to obtain an extra unit of health gain) was calculated by dividing the difference between the total cost by the difference of effects in the intervention and control districts.
- The incremental net benefit (INB) was calculated by valuing additional effect (∆E) in dollars and then subtracting the associated additional cost (∆C): INB = (∆E x λ) - ∆C, where λ is willingness to pay (WTP) for a 1-unit gain of effect .
Willingness to pay (WTP) and decision rule on cost-effectiveness
Willingness to pay
Three WTP was adopted:
- WTP 1) for LLINs delivered (US$ 1.32 per LLIN - adopted by the Global Fund for Mozambique in-country mass free campaign budget planning );
- WTP 2) for LLINs delivered plus LLIN purchases cost (US$ 9.12 per LLIN - US$ 1.32 + US$ 7.8 which was the maximum inter-quartile purchase cost for the period 2005 – 2012 ); and
- WTP 3) for HHs achieving UC (US$ 3.30 per household). This third WTP was determined by multiplying the average number of HH members (five)  by US$ 1.32, and dividing by two (one LLIN for every two persons).
The cost-effectiveness decision rule was based on INB results. Two INB was calculated: INB for delivered LLIN (using WTP 1 and 2) and INB for HHs achieving UC (using WTP 3). A positive INB means that the new intervention extra benefits (∆E x λ) outweighs its extra costs (∆C), i.e., the new intervention is deemed cost-effective. Conversely, when INB is less than 0 (negative INB), the new intervention is not cost-effective .
A one-way deterministic sensitivity analysis was performed on the following parameters and assumptions: i) free warehouses for storing LLINs; ii) transport cost (±50%); and iii) costs of LLINs purchase (-25%, -50%). Base case cost analysis was used to calculate the percentage of deviation in the intervention and control districts. For the first two parameters, the base case was the ACER and ICER per LLIN delivered. For the third parameter, the base case was also ACER and ICER per LLIN delivered but also included the 2014 purchase cost of US$ 3.63 per LLIN for the planned 344,770 LLINs in the intervention and 284,873 LLINs in the control districts.
The US$ 3.63 per LLIN was based on the unit cost for Disease Control Technologies Royal Sentry® rectangular LLINs 190 x 180 x 180 cm of US$ 3.19; procurement fee 1.50%; outbound transport charges 11.94%; transport insurance charges 0.14%; question and answer charges 0.09%; and pre-shipment inspection charges 0.12%.