Costs associated with the smartphone app for weight loss promotion intervention.

Cost componenta	Cost (NZ $)	Details
One-off costs for the promotion of the smartphone apps	$72,000	The cost of promotion on relevant government-funded websites (Ministry of Health, district health board, Health Promotion Agency [HPA]). Estimate based on the HPA Breakfast-eaters campaign (Personal Communication, HPA, October 2015) for Web-based promotions (Google adwords, Facebook adverts, promoting Facebook posts, etc) to drive consumers to the Breakfast-eaters website
Mass media promotion	$2,791,000	Cost of 1 year mass media promotion (assumed to be the same as the 2013-14 Quitline marketing budget; the promotion required for this intervention was assumed to be similar to the level of marketing undertaken by Quitline); $2,887,000) [21]. The cost of Quitline advertising and promotion for the 12-month period in 2013-2014 was NZ $2,165,000, and the staff management costs for “marketing and communications” were NZ $722,000 [21]. These 2014 costs were consumer price index–adjusted to the 2011 base year, giving an annual cost of NZ $2,791,000
Identifying top apps	$20,000	Cost of a one-off upgrade of previous New Zealand work [12] in identifying the top 5 apps for Apple and Android weight loss apps for promotion on the websites (NZ $20,000 contract)
Total intervention costs	$2,883,000	Uncertainty: estimated at SD±20% of the point estimate, gamma distribution. Correlated (0.75) with intervention parameters (access to smartphones, exposure to promotion campaign, and weight loss app downloaded)

^aCosts to the individual were not included as they were out of scope with the health system perspective used but would include a proportion of the cost of a smartphone and its running costs, the usually trivial cost of the app (though most are free) and any costs (or cost-savings) for dietary changes and increased physical activity.