Appendix 1: Background data and details of analyses used in the study

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1 Appendix 1: Background data and details of analyses used in the study Table A Model parameters Parameter Baseline Range Source Target population (F, aged <25) 3,075,000 - Derived from NCSP Target population (M, aged <25) 3,075,000 - report Screening coverage (F) 24% 24 66% 1 < Positivity in screened (F) 8% - ng.nhs.uk/ps/assets/pdfs/public Screening coverage (M) 8% 8 50% ations/reports/ncspa-rprt- 08_09.pdf> Positivity in screened (M) 6% - Positivity in those partner notified 65% - Cost per screen (M/F) 45 33, 56 NAO report 2 Cost of treatment of positive case 87 - Costing guidance initiative 3 Cost per screen (excluding PN cost) Derived from re-analysis of Cost of PN per positive index, excluding 27 9, 13, cost guidance initiative data test and treatment costs 27 Total cost of PN including test and treatment costs Partner notification efficacy (PNe) (partners confirmed treated per index) Vital Signs Index 4

2 Table B Detailed model description The model is a series of calculations following logically from the initial model assumptions. The advantage of this simple approach is that the calculations are fully replicable and can be updated quickly as new data become available and easily applied in other settings, locally or internationally. Abbreviation Calculation E.g. Target population (i.e ) N TARGET_M, N TARGET_F Number screened X SCREENED_M, X SCREENED_F Positivity in those screened Pos SCREENED_M, Pos SCREENED_F Positivity in those partner notifiied Pos PN_M, Pos PN_F Partner notification efficacy PNe Number of partners notified per index Proportion of diagnosed infections notified and treated D TREATED Estimated prevalence eprev_f, eprev_m Cost of a screen c SCREEN Cost of treatment of positive c POS Cost of PN, excluding tests and treatment c PN_EXC Cost of partner notification c PN = c PN_EXC + c POS Screening coverage Cov F = _ _ 24% Screening coverage Cov M = _ _ 8% F positive screened CT SCREEN_F = X SCREENED_F * Pos SCREENED_F 56,826 M positive screened CT SCREEN_M = X SCREENED_M * Pos SCREENED_M 15,744 Total positive through screening CT SCREEN = CT SCREENED_F + CT SCREENED_M 72,570 F PN from male index PN F = PNe * CT SCREENED_M 6,298 M PN from F index PN M = PNe * CT SCREENED_F 22,730 Total PN PN = PN F +PN M 29,028 M positive through PN CT PN_M = PN M * Pos PN 14,775 F positive through PN CT PN_F = PN F * Pos PN 4,093 Positive treated through PN CT PN = CT PN_F +CT PN_M 18,868 Number infected & treated CT TREATED = D TREATED *(CT PN + CT SCREENED ) 91,438 Ratio F to M tested F:M tested = _ 2.77 Ratio F to M infected and treated F:M treated Estimated fraction of prevalent infections treated p(treated) = _ = _ _ _ _ _ _ Cost of screening women, million Cost SCREEN_F = X SCREENED_F * c SCREEN /1,000, Cost of screening men, million Cost SCREEN_M =X SCREENED_M * c SCREEN /1,000, Total cost of screening, million Cost SCREEN = Cost SCREEN_F + Cost SCREEN_M Cost of PN in men, million Cost PN_F = PN M * c PN /1,000, Cost of PN for women, million Cost PN_M = PN F * c PN /1,000, Total cost of PN, million Cost PN = Cost PN_F + Cost PN_M 3.31 Total cost of screening and PN, million Total_Cost = Cost PN + Cost SCREEN Cost per infected male treated, Cost INF_M = _ _ _ _ 437 Cost per infected female treated, Cost INF_F Cost per treated infection (M& F), Cost INF = _ PN % total screening cost p(pn cost) = _ % %

3 Summary of methods to estimate partner notification costs for programme areas As the partner notification costs were part of a larger analysis, only the components directly relating to PN were included here. The costs included direct and indirect clinical time (i.e. cost per minute), multiplied by the number of minutes for a particular activity. Consumable unit costs were also included (phone, fax etc). The indirect and overhead costs of running the Chlamydia Screening Offices (CSOs) were also included in the total costs. Partner notification data were collected through semi-structured interviews with the CSO teams and NCSP service providers (2008/9). Where data were missing or not available, assumptions were made based on feedback from staff. The costs for 4 steps were estimated for the CSO involvement (initial contact with positive index, supported PN in which clinical staff rather than clients notify partners, partners calling the CSO, and following up index positives and partners) and for the screening venue involvement. Partner notification was delivered by the coordinating CSO team and by the individual screening/treatment venues. Costs from both sites were estimated and included in the model. To capture the costs of delivering PN in GUM clinics (as many positive clients were referred to GUM for their treatment and PN), a proportion of the national GUM tariff was taken (estimated to be 33% of the treatment visit 3 ). This was also done for GP & Pharmacy LES payments if it was explicitly used for treatment as per their agreement. If a screen is delivered through a CASH service, this was based on the block contract. National costs of delivering screening (i.e. marketing, coordination, etc) were excluded. Costs are outlined in Table C below.

4 Table C Cost of partner notification activity in three modelled programme areas of NCSP in England Low Medium High CSO Cost, Proportion of positives Cost, Proportion of positives Cost, Proportion of positives Initial contact with positive index client % % % Provider partner notification % % Partners call in % - - Follow-up positives % Follow-up partners % Sites CASH % % % GP % % % Pharmacy % - 2% GUM % % % Brook % % Other* - 4% % Total cost per PN per positive index ** *While there was activity through other channels, there were no costs associated with it **If 100% provider PN and follow-up partners is assumed for Model 3, then the estimated cost of PN per positive index increases to Key : CASH Contraceptive and Sexual Health, GUM Genito-urinary medicine, GP General Practice, CSO Chlamydia screening office

5 Efficacy of partner notification Data were provided by the NCSP for three selected PCTs from Jan 1 st 2009 to 30 th Sept 2009, including the number of reported partners and number of partners confirmed notified and treated. Partner notification efficacy (PN efficacy) is the average number of partners confirmed as treated (PNt) per index case (Ic) for each site. This is the combined average for men and women since data on confirmed treatment were not available by gender. Table D Partner notification activity reported in three example NCSP programme areas in England Site 1 - Low Site 2 - Medium Site 3 - High Partners reported per index Partners contacted (any method) per index Partner notification efficacy (partners confirmed treated per index) The data presented in Table D should only be taken as broadly illustrative as there were discrepancies between the site definitions such that the data are not based on the same denominator population for the cost analysis. In at least one site there were known to be problems in extracting the relevant data from their records so the efficacy calculation was not felt to accurately reflect the amount of PN which had occurred. The PN pathway used by the site 3 - high intensity was the most similar to that recommended by an expert working group on behalf of the National Screening Advisory Group (NCSAG). However, the PN efficacy for this site was reported as 0.2 partners per index, which was lower than 0.3 reported by the low and medium intensity sites. After discussion with the site coordinator, it was felt that this reflected problems in the data collection system rather than necessarily poor PN outcomes, which has since been updated. Finally there were also some potential differences in definition which led to apparent inconsistencies within the data, e.g. Site 2 reported more partners treated than contacted (by any method) per index. Therefore the decision was taken not to relate these costs directly into an estimate of PN cost effectiveness but instead to use the range of values reported in VSI to estimate a possible range of cost-effectiveness. The problem of adequately recording and reporting PN outcomes remains an important obstacle to improving understanding of this process.

6 Figure A Impact of increasing coverage on the cost per infection treated Cost per infection treated Cost per infection treated (F coverage: for M <24%, F=24%; for M>=24%, F=M) Cost per infection treated (F Coverage: F = M + 16%) Male coverage The y-axis crosses at baseline male coverage value of 8%. Two alternative situations are compared for female coverage: 1) Assume female coverage is fixed at 24% for male coverage below 24% then equal to male coverage at higher coverage levels or 2) assume that female coverage is 16% higher than male coverage for all levels of male coverage.

7 Figure B Effect of changing PN efficacy, assuming constant cost of PN or linearly increase in average cost with increasing PN efficacy. 600 Cost per infection treated, Cost of PNrelated to efficacy Constant cost 218 Linear increase 54 to 218 Constant cost 114 Linear increase 54 to Partner notification efficacy, partners treated per index

8 Table E Scenario analysis for estimating cost-effectiveness of interventions to increase screening coverage and efficacy of partner notification: Effectiveness and gender equity of interventions Baseline PN 0.4, M 8%, F 24% Scenario 1 Scenario 2 PN 0.8 M coverage 24% Scenario 3 Coverage overall 35% Scenario 4 Scenario 5 Scenario 6 Scenario 7 PN 0.25 PN 0.6 PN 1 M cov 16% PN 0.4 Scenario 8 M cov 16% PN 0.25 Scenario 9 M cov 24% PN 0.25 Scenario 10 M cov 16% PN 0.8 Scenario 11 M cov 24% PN 0.8 Female coverage Male coverage PN efficacy F screened 738, , ,000 1,322, , , , , , , , ,000 M screened 246, , , , , , , , , , , ,000 Total screened 984, ,000 1,476,000 2,152, , , ,000 1,230,000 1,230,000 1,476,000 1,230,000 1,476,000 F positive screened 56,826 56,826 56, ,813 56,826 56,826 56,826 56,826 56,826 56,826 56,826 56,826 M positive screened 15,744 15,744 47,232 53,136 15,744 15,744 15,744 31,488 31,488 47,232 31,488 47,232 Total positive through screening 72,570 72, , ,949 72,570 72,570 72,570 88,314 88, ,058 88, ,058 F PN from male index 6,298 12,595 18,893 21,254 3,936 9,446 15,744 12,595 7,872 11,808 25,190 37,786 M PN from F index 22,730 45,461 22,730 40,725 14,207 34,096 56,826 22,730 14,207 14,207 45,461 45,461 Total PN 29,028 58,056 41,623 61,980 18,143 43,542 72,570 35,326 22,079 26,015 70,651 83,246 M positive through PN 14,775 29,550 14,775 26,471 9,234 22,162 36,937 14,775 9,234 9,234 29,550 29,550 F positive through PN 4,093 8,187 12,280 13,815 2,558 6,140 10,234 8,187 5,117 7,675 16,374 24,561 Positive treated through PN 18,868 37,736 27,055 40,287 11,793 28,302 47,171 22,962 14,351 16,909 45,923 54,110 Number infected & treated 91, , , ,236 84, , , , , , , ,168 Ratio F to M tested Ratio F to M infected and treated Estimated fraction of prevalent infections 29.7% 35.9% 42.6% 63.5% 27.4% 32.8% 38.9% 36.2% 33.4% 39.3% 43.7% 51.4% Estimated fraction of prevalent infections diagnosed (ignores dynamic effects), assuming 5% prevalence or 307,500 cases

9 Table E continued (Cost and cost-effectiveness) Scenario analysis for estimating cost-effectiveness of interventions to increase screening coverage and efficacy of partner notification Baseline PN 0.4, M 8%, F 24% Scenario 1 Scenario 2 PN 0.8 M coverage 24% Scenario 3 Coverage overall 35% Scenario 4 Scenario 5 Scenario 6 Scenario 7 PN 0.25 PN 0.6 PN 1 M cov 16% PN 0.4 Scenario 8 M cov 16% PN 0.25 Scenario 9 M cov 24% PN 0.25 Scenario 10 M cov 16% PN 0.8 Female coverage Male coverage PN efficacy Cost of screening women, million Cost of screening men, million Total cost of screening, million Cost of PN in men, million Cost of PN for women, million Total cost of PN, million Total cost of screening and PN, million Lower - Total cost of screening plus PN Upper - Total cost of screening plus PN Cost per infected male treated, Cost per infected female treated, Cost per treated infection (M& F), Lower - cost per treated infection (M& F) Upper - cost per treated infection (M& F) PN % total screening cost 7.2% 13.4% 6.9% 7.0% 4.6% 10.4% 16.2% 7.0% 4.5% 4.4% 13.0% 12.8% Lower - PN % total screening cost 9.8% 17.8% 9.4% 9.3% 6.3% 14.0% 21.3% 9.5% 6.2% 6.1% 17.4% 17.2% Upper - PN % total screening cost 5.8% 11.0% 5.6% 5.7% 3.7% 8.5% 13.4% 5.7% 3.6% 3.6% 10.8% 10.6% All costs estimated assuming a screen costs on average except lower/upper cost estimates which are for or screen cost respectively. Scenario 11 M cov 24% PN 0.8

10 Reference List (1) NCSP. NCSP annual report The Bigger Picture (2) NAO (National Audit Office). Young people's sexual health: the National Chlamydia Screening Programme (3) National Chlamydia Screening Programme. Guidance for commissioners on the costs of providing chlamydia screening in primary care and the community: a review of costs in practice across England in London (4) NCSP. VSI data tables for 08-09: England April March Relevant websites and web documents National Chlamydia Screening Programme team. National Chlamydia Screening Programme. (accessed May 2010). Department of Health. VSB13: Chlamydia Prevalence (Screening). (accessed May 2010). National Audit Office. Department of Health Young people's sexual health: the National Chlamydia Screening Programme National Chlamydia Screening Programme. Guidance for commissioners on the costs of providing chlamydia screening in primary care and the community: a review of costs in practice across England in ance_dec09.pdf National Chlamydia Screening Programme. The Bigger Picture: The National Chlamydia Screening Programme 2008/09 Annual Report National Chlamydia Screening Programme. Men too. Department of Health/NHS Employers. Creating a Gender Equality Scheme: A Practical Guide for the NHS et/dh_ pdf Horner P, Boag F UK National Guideline for the Management of Genital Tract Infection with Chlamydia trachomatis. BASHH National Chlamydia Screening Programme. VSI 2009/10 How to get there: Top tips for meeting and surpassing the target. National Chlamydia Screening Programme. Involving young men in chlamydia screening: A practical guide