Table 2.
Parameters used in the model and their sampling distribution for the probabilistic sensitivity analysis
| Parameters | Mean (SE) | Distribution | Reference |
|---|---|---|---|
| Baseline Parameters | |||
| Discount Rate for both costs and outcomes | 3.5 % | DOH, 2013 | |
| Age start in the model (years) | 11 | ||
| PPP conversion factor, (Pesos per 1$) | 24.8 | World data bank, 2013 | |
| Epidemiological Parameters | |||
| Prevalence of HPV infection | 0.100 (0.064) | Beta | Myers et al. [22] |
| Prevalence of CIN1 | 0.010 (0.010) | Beta | Myers et al. [22] |
| Age specific (y) incidence of HPV infection | |||
| 11 | 0.019 (0.007) | ||
| 15 | 0.100 (0.038) | Beta | Myers et al. [22] |
| 16 | 0.100 (0.038) | Beta | |
| 17 | 0.120 (0.046) | Beta | |
| 18 | 0.150 (0.057) | Beta | |
| 19 | 0.170 (0.065) | Beta | |
| 20 | 0.150 (0.057) | Beta | |
| 21 | 0.120 (0.046) | Beta | |
| 22 | 0.100 (0.038) | Beta | |
| 23 | 0.100 (0.038) | Beta | |
| 24 | 0.050 (0.019) | Beta | |
| 30 | 0.010 (0.004) | Beta | |
| 50+ | 0.005 (0.002) | Beta | |
| Yearly Transitional Probability | |||
| HPV infection to CIN1 | 0.072 (0.015) | Beta | Myers et al. [22] |
| CIN1 to CIN2/3 (age [y]) | |||
| 15 | 0.017 (0.010) | Beta | Myers et al. [22] |
| 35 | 0.069 (0.013) | Beta | |
| CIN 2/3 to invasive CA | 0.050 (0.008) | Beta | |
| Stage I to Stage II | 0.438 (0.351) | Beta | Myers et al. [22] |
| Stage II to Stage III | 0.536 (0.351) | Beta | |
| Stage III to Stage IV | 0.684 (0.140) | Beta | |
| Regression | |||
| Age-specific (y) probability of regression: HPV infection to healthy | Myers et al. [22] | ||
| 15 | 0.552 (0.084) | Beta | |
| 25 | 0.370 (0.033) | Beta | |
| 30 | 0.103 (0.018) | Beta | |
| Age-specific (y): CIN1 to HPV infection or healthy | Myers et al. [22] | ||
| 15 | 0.161 (0.024) | Beta | |
| 35 | 0.082 (0.021) | Beta | |
| CIN 2/3 to CIN1 or healthy | 0.069 (0.013) | Beta | Myers et al. [22] |
| Proportion of CIN1 reverting to healthy | 0.900 (0.128) | Beta | |
| Proportion of CIN2/3 reverting to healthy | 0.500 (0.128) | Beta | |
| Proportion of having symptoms | Myers et al. [22] | ||
| Stage I | 0.150 (0.150) | Beta | |
| Stage II | 0.225 (0.225) | Beta | |
| Stage III | 0.600 (0.600) | Beta | |
| Stage IV | 0.900 (0.900) | Beta | |
| Weibull survival by CA stage and patient age (y) | |||
| Stage I | |||
| constant | −8.749 (1.259) | Log-Normal | Praditsitthikorn et al. [17] |
| Age coefficient | 0.041 (0.020) | Log-Normal | |
| Gamma | 0.589 (1.139) | Log-Normal | |
| Stage II | |||
| constant | −7.066 (0.934) | Log-Normal | |
| Age coefficient | −0.014 (0.011) | Log-Normal | |
| Gamma | 0.919 (1.120) | Log-Normal | |
| Stage III | |||
| constant | −6.778 (0.891) | Log-Normal | |
| Age coefficient | 0.023 (0.011) | Log-Normal | |
| Gamma | 0.675 (1.098) | Log-Normal | |
| Stage IV | |||
| constant | −3.863 (1.217) | Log-Normal | |
| Age coefficient | −0.055 (0.022) | Log-Normal | |
| Gamma | 1.004 (1.226) | Log-Normal | |
| Program Effectiveness Parameters | |||
| Pap Smear | |||
| Sensitivity for pre-invasive | 0.552 (0.070) | Beta | Sritipsukho, [27] |
| Specificity | 0.915 (0.013) | Beta | |
| VIA | |||
| Sensitivity for pre-invasive | 0.716 (0.025) | Beta | Sritipsukho, [27] |
| Specificity | 0.793 (0.011) | Beta | |
| HPV Vaccine | |||
| Relative risk of persistence HPV infection, 1-year | 0.26 (0.064) | Beta | Rambout et al. [25] |
| Programme Acceptability | |||
| Pap Smear | 0.08 | University of the Philippines-Department of Health Cervical Cancer Screening Study Group, 2001 [7] | |
| Proportion of Patients with CIN 2/3 | |||
| Receiving cryosurgery | 1.000 (1.000) | Beta | Goldie et al. [44] |
| Receiving cold knife conisation | 0.125 (0.125) | Beta | Goldie et al. [44] |
| Receiving simple hysterectomy | 0.125 (0.125) | Beta | Goldie et al. [44] |
| Incidence of OP visit for treating minor complications from cryosurgery | 0.05 (0.05) | Beta | Goldie et al. [44] |
| Incidence of IP visit for treating major complications from cryosurgery | 0.01 (0.01) | Beta | Goldie et al. [44] |
| Annual rate of OP visits | Praditsitthikorn et al. [17] | ||
| Initial Stage | 25.48 (1.41) | Gamma | |
| Remission Stage | 7.14 (0.59) | Gamma | |
| Persistence Stage | 38.53 (7.77) | Gamma | |
| Recurrence Stage | 13.37 (2.02) | Gamma | |
| Annual rate of IP visits | Praditsitthikorn et al. [17] | ||
| Initial Stage | 0.77 (0.10) | Gamma | |
| Remission Stage | 0.15(0.04) | Gamma | |
| Persistence Stage | 0.87 (0.43) | Gamma | |
| Recurrence Stage | 1.64 (0.31) | Gamma | |
| Costing Parameters (in Php) | |||
| Direct Medical Costs of Screening (per visit) | |||
| Pap smear | 965 (965) | Gamma | Primary data collected by the authors |
| VIA | 500 (500) | Gamma | Primary data collected by the authors |
| Cost of follow up for Pap screening | 500 (500) | Gamma | Primary data collected by the authors |
| Cost of HPV vaccination (three doses) | 2,736 (2,376) | Gamma | Price Offer to the government |
| Cost of HPV booster doses | 800 (800) | Gamma | Price Offer to the government |
| Cost of Vaccine delivery and administration (per dose) | 112 (112) | Gamma | DOH DPCB, 2013 |
| Unit cost of colcoscopy/ biopsy | 1,120 (1,120) | Gamma | PHIC, 2013 |
| Unit costs | |||
| Cryotherapy | 1,500 (1,500) | Gamma | Primary data collected by the authors |
| Loop Electrosurgical Extraction Procedure (LEEP) | 12,644.54 (12,644.54) | Gamma | PHIC, 2013 |
| Cold knife conisation | 8100.36 (8100.36) | Gamma | PHIC, 2013 |
| Simple hysterectomy | 41,362.67 (41,362.67) | Gamma | PHIC, 2013 |
| Cost of hospitalization day (Php per day) | 500 (500) | Gamma | Health facilities |
| Hospitalization days | |||
| Cold knife conisation | 1 | Gamma | Expert opinion |
| Simple hysterectomy | 5 | Gamma | Expert opinion/ Primary data collected by the authors |
| Medical cost of follow – up | |||
| Cryosurgery | 1,000 (255.10) | Gamma | Primary data collected by the authors |
| LEEP/ Cold knife conisation/ Simple hysterectomy | 750 (127.55) | Gamma | Primary data collected by the authors |
| Unit Cost | |||
| Cervical CA staging | 4,485 (765.31) | Gamma | Primary data collected by the authors |
| Treating complications from cryosurgery (minor) | 510.08 (510.08) | Gamma | Primary data collected by the authors |
| Treating complications from cryosurgery (major) | 512.48 (512.48) | Gamma | Primary data collected by the authors |
| Annual Costs for treatment of invasive cervical CA | |||
| Initial Stage | |||
| -Stage I | 77,873.00 (39,073.469) | PHIC 2013 | |
| -Stage II | 77,873.00 | PHIC 2013 | |
| -Stage III | 106,390.05 | PHIC 2013 | |
| -Stage IV | 106,390.05 | PHIC 2013 | |
| Remission Stage | |||
| -Stage I | 16,523 | PHIC 2013 | |
| -Stage II | 16,115 | PHIC 2013 | |
| -Stage III | 20,618 | PHIC 2013 | |
| -Stage IV | 27,310 | PHIC 2013 | |
| Persistence Stage | |||
| -Stage I | 112,093 | PHIC 2013 | |
| -Stage II | 93,256 | PHIC 2013 | |
| -Stage III | 118,350 | PHIC 2013 | |
| -Stage IV | 117,801 | PHIC 2013 | |
| Recurrence | |||
| -Stage I | 65,818 | PHIC 2013 | |
| -Stage II | 63,747 | PHIC 2013 | |
| -Stage III | 83,512 | PHIC 2013 | |
| -Stage IV | 111,233 | PHIC 2013 | |
| Utility Parameters | |||
| Healthy Stage or CIN1-3 without complication | 1.00 (1.00) | Beta | Praditsitthikorn et al. [17] |
| Initial Stage | |||
| -Stage I | 0.74 (0.01) | Beta | |
| -Stage II | 0.76 (0.01) | Beta | |
| -Stage III | 0.72 (0.02) | Beta | |
| -Stage IV | 0.63 (0.03) | Beta | |
| Remission Stage | |||
| -Stage I | 0.79 (0.01) | Beta | |
| -Stage II | 0.79 (0.01) | Beta | |
| -Stage III | 0.81 (0.01) | Beta | |
| -Stage IV | 0.85 (0.05) | Beta | |
| Persistence Stage | |||
| -Stage I | 0.80 (0.20) | Beta | |
| -Stage II | 0.80 (0.04) | Beta | |
| -Stage III | 0.65 (0.05) | Beta | |
| -Stage IV | 0.45 (0.05) | Beta | |
| Recurrence | |||
| -Stage I | 0.80 (0.03) | Beta | |
| -Stage II | 0.68 (0.02) | Beta | |
| -Stage III | 0.66 (0.04) | Beta | |
| -Stage IV | 0.81 (0.08) | Beta | |
DOH - Department of Health; DPCB - Disease Prevention and Control Bureau; PHIC - Philippine Health Insurance Corporation