Appendix E: PSA Parameters Variable Mean Value SE Parameterisation Distribution used ACR response rates Individual treatment response rate n/a Use N*100=alpha of the one parameter Gamma distribution for each ACR category Dirichlet HAQ score adjustments (initial improvement) Non-responder 0.14 0.02 Taken from post-hoc analysis of OPTION, LITHE and TOWARD [3-5] (see Appendix A) Normal ACR20 responder 0.46 0.02 ACR50 responder 0.68 0.03 ACR70 responder 0.9 0.03 Long term changes: HAQ progression bDMARD 0 0.0057 Assume 0.0225 (sDMARD value) is the upper limit of CI and 0 is the mean value in the acceptable range Normal sDMARD 0.0225 0.0019 Assume 0.03 (palliative care) is the upper limit of CI and 0.0225 is the mean value in the acceptable range Palliative care 0.03 n/a Linked to sDMARD value Use lognormal on the difference with sDMARD HAQ progression: 1.33 Rebound effect 1 n/a Assumption +/-20% Uniform [0.8, 1.2] VAS pain score Baseline 75.00 1.26 Alpha and beta parameters calculated using mean value and SE reported in Hyrich 2009 [1] Beta (Generated probabilistic value is multiplied by 100) Non-responder 4.02 0.79 Alpha and beta parameters calculated using mean value and SE taken from OPTION, LITHE and TOWARD [3-5] (see Appendix A) ACR20 responder 23.97 0.86 ACR50 responder 36 0.95 ACR70 responder 45.96 1.26 Palliative care 55 1.2755 Results of clinician survey Assume the CI is between 50-60 Mortality Mortality risk 1.33 0.1304 Wolfe et al. 1994 [2] Lognormal Cost Outpatient visit (first attendance) 214 5.91 Based on NHS reference costs [7] Normal
Outpatient visit (subsequent), GP visit, Full blood count, ESR, LFT, U&E , Chest X-ray tests n/a n/a Values not sampled independently but linked to outpatient visit sample n/a Inpatient cost 240 48.00 CIs are derived by assuming lower and upper limits are ±20% of the mean value Lognormal Infusion administration 171 34.27 Home visit 27 5.40 Proportion of patients that require a nurse visit for subcutaneous injection 0.1 0.02 Beta Average annual income of the population (indirect cost) 26989 2698.90 CIs are derived by assuming lower and upper limits are ±10% of the mean value Lognormal AE (pneumonia) 2047 37.26 Based on NHS reference costs [7] Normal AE (palliative care) 314.17 62.83 CIs are derived by assuming lower and upper limits are ±20% of the mean value Lognormal AE disutility bDMARDs 0.986 0.0036 Assumes upper limit of CI=1 (no disutility), and the respective mean is used to create an acceptable range. Beta sDMARDs 0.970032841 0.0076 Palliative care 0.970032841 0.0076 AE event probabilities Certolizumab pegol 0.113 0.0742 Singh et al. 2012 [6] Beta bDMARD (excluding certolizumab pegol) 0.035 0.0048 Treatment Discontinuation Discontinuation (Loglogistic model) 0 1 Based on the variance covariance derived from treatment discontinuation analysis (Appendix B) Multinomial Normal ACR, American College of Rheumatology; AE, adverse event; American College of Rheumatology, ACR; bDMARDs, biologic disease modifying anti-rheumatic drug; CI, confidence interval; ESR, erythrocyte sedimentation rate; GP, general practitioner; HAQ, Health Assessment Questionnaire; LFT, liver function test; N, sample size; n/a, not applicable; sDMARD, synthetic disease modifying anti-rheumatic drug; U&E , urea and electrolytes; VAS, visual analogue scale