Table 4.

Impact of model assumptions on the discounted incremental cost-effectiveness ratio (ICER) evaluating ‘5-yearly self-sampling’ and ‘10-yearly self-sampling’ compared with the current 2-reminder letter policy in Norway

Respondent screening historya	Sensitivity analysis scenario	‘5-yearly self- sampling’ ICERb	‘10-yearly self- sampling’ ICERb	Current 2- reminder letter policy
Scenario A: 5-yearly Self- sampling respondents are moderate under-screeners (Figure 1)	Base case	$29,627	$95,486	Dominated
	hrHPV+ compliance 100%	$32,408	$144,002	Dominated
	Relative test specificity of 1	$29,475	$103,772	Dominated
	Relative SS sensitivity of 0.9	$29,800	$77,719	Dominated
	No excess office-based exams	$29,004	$126,030	Dominated
	No substitution behaviorc	Dominated	$30,768	Dominated
	Direct medical costs only	$16,209	$76,536	Dominated
	’5-yearly SS’ participation 8%d	$29,910	$67,745	Dominated
	’5-yearly SS’ participation 12%d	$29,268	$509, 890	Dominated
	’10-yearly SS’ participation 4%d	$29,627	$209,944	Dominated
	’10-yearly SS’ participation 8%d	$29,627	$61,325	Dominated
Scenario B: 5-yearly self- sampling respondents are moderate and severe under-screeners (Figure 1)	Base case	$29,423	Dominated	Dominated
	hrHPV+ compliance 100%	$32,116	Dominated	Dominated
	Relative test specificity of 1	$29,274	Dominated	Dominated
	Relative SS sensitivity of 0.9	$29,590	Dominated	Dominated
	No excess office-based exams	$28,814	Dominated	Dominated
	No substitution behaviorc	$72,362	$30,768	Dominated
	Direct medical costs only	$16,067	Dominated	Dominated
	’5-yearly SS’ participation 8%d	$29,802	$161,611	Dominated
	’5-yearly SS’ participation 12%d	$29,054	Dominated	Dominated
	’10-yearly SS’ participation 4%d	$29,423	Dominated	Dominated
	’10-yearly SS’ participation 8%d	$29,423	Dominated	Dominated

hrHPV+: high-risk HPV-positive.

^aRefers only to ‘5-yearly self-sampling’. Moderate under-screening histories assumed women screen every 8-, or 10-years in the absence of self-sampling, and moderate and severe under-screening histories assumed women screen every 8-, 10-, 20-years or never-screened in the absence of self-sampling. A single self-sampling scenario was considered for the ’10-yearly self-sampling’ strategy (see Figure 1);

^bCost per quality-adjusted life year gained. Quality of life adjustments ranged from a health state utility weight of 0 (death) to 1 (perfect health). Weights for cervical cancer varied according to stage (local: 0.76 for five years; regional: 0.67 for five years; distant: 0.48 five years). Disease specific utility weights were multiplied to baseline age-specific utility weights from Denmark (17) to estimate overall utility;

^cRank order of strategies changed. ‘5-yearly self-sampling’ was more costly but less effective than 10-yearly self-sampling,

^dAssumes substitution behavior continues;

^eFor more detailed information on cost calculations, please visit the author’s website at: http://www.med.uio.no/helsam/english/research/projects/preventive-strategies-hpv/harvardmodel-norway-technicalappendix.pdf. (US $1=NOK6.30)