Economic analysis
Acne, MP, PCOS
REGRESSION, SECONDARY, POLYCYSTIC OVARY SYNDROME, ACNE
The base-case cost-utility analysis (CUA) and secondary cost-effectiveness analysis (CEA) incorporated all randomised participants with complete cost and outcome data. Given the 24-week time-horizon, costs and benefits were not discounted.The base-case CUA estimated the incremental cost per QALY (incremental cost-effectiveness ratio, ICER) to enable comparison with the cost-utility of other interventions. The incremental cost (95% CI) and QALY change (95% CI) between groups was estimated unadjusted and adjusted for randomisation stratification variables (centre, baseline severity (IGA <3 vs ≥3)) and baseline variables (including Acne-QoL symptom subscale score, resource use costs, EQ-5D score and use of topical treatments (Y/N)). In line with NICE guidance,A CEA estimated the incremental cost per unit change on the Acne-QoL symptom subscale score. The incremental cost (95% CI) and Acne-QoL symptom subscale change (95% CI) between groups was estimated unadjusted and adjusted as described for the base-case CUA. The CUA and CEA were undertaken using a regression-based approach (seemingly unrelated regression equations).To estimate the level of uncertainty associated with the decision regarding cost-effectiveness, Fieller’s theorem was used to calculateSeveral sensitivity analyses were agreed and specified in the health economic analysis plan (HEAP) before analysis to explore key uncertainties around important parameters in the economic evaluation. The impact of missing data on cost-effectiveness estimates was explored by undertaking multiple imputation (MI) (SA1), assuming that the data were missing at random and using chained equations to handle the missing cost and outcome data.

Unit costs (UK£ sterling, 2020/2021 financial year)*Inflated to 2021 prices as per NHSCII Pay & Prices.GP, General Practitioner; HCP, Healthcare Professional; ONS, Office for National Statistics; PCOS, Polycystic Ovary Syndrome; PSSRU, Personal Social Services Research Unit.Cost-utility analyses and cost-effectiveness analyses results, including sensitivity analyses and subgroup analysis*Probability of being cost-effective at the threshold (λ) of £20,000 and £30,000 per QALY. Adjusted analyses, adjusted for stratification variables (centre, baseline severity [IGA<3 vs. ≥3]) and baseline variables (Acne QoL symptom subscale score, use of topical treatments, utility score based on EQ-5D, total costs).†Comparing spironolactone plus routine topical treatment to no active systemic treatment plus routine topical treatment.‡Threshold analysis conducted using a £30,000 threshold, as described in the methods. The value given represents the incremental QALY benefit below which spironolactone compared with oral antibiotic would switch from cost-effective to not cost-effective.CCA, complete case analysis; CEA, cost-effectiveness Analysis; CEAC, cost-effectiveness acceptability curve; CUA, cost-utility analysis; ICER, incremental cost-effectiveness ratio; N s/N p, number randomised to spironolactone/placebo who were included in the analysis; QALY, quality-adjusted life year.Stata MP V.17 was used to conduct the analyses. A HEAP was written and followed; a copy is available from the corresponding author.