* Candidate for the Lee B. Lusted Student Prize Competition
Method: We developed a dynamic compartmental model of the HIV epidemic in a population of non-IDUs, IDUs who inject opiates, and IDUs on methadone. The parameters for the model were based on data from
Result: With no incremental interventions, HIV prevalence reached 71.7% in IDUs and 1.22% in non-IDUs after 20 years. Increasing methadone access to 25% of IDUs was the most cost-effective strategy and generated the lowest final HIV prevalence in both IDUs (49.8%) and the general population (0.7%). This strategy averted 5300 infections and added 35,000 QALYs for a cost of $740/QALY gained. Expanding HAART averted fewer infections, even with 80% coverage: 3700 infections were prevented, adding 57,000 QALYs at a cost of $4,400/QALY gained. Increasing both methadone (to 3.1% of IDUs) and HAART access (to 50% of eligible individuals) averted 3150 infections, adding 44,600 QALYs at a cost of $4,100/QALY gained. Treating a limited number of IDUs (10%) with HAART but offering 80% HAART coverage to eligible non-IDUs averted only 1,680 infections, adding 40,200 QALYs at a cost of $4,800/QALY gained.
Conclusion: Methadone substitution therapy is a highly cost-effective option for addressing the growing HIV epidemic in
Purpose: As 2nd-line antiretroviral therapy (ART) availability increases in resource-limited settings, questions remain about the value of laboratory monitoring to guide treatment decisions. Our objective was to assess the incremental benefits and cost-effectiveness of CD4 count and HIV RNA tests to guide the timing of switching ART in HIV-infected patients.
Methods: In a treatment-eligible cohort in Côte d’Ivoire, West Africa, we used a state-transition model (CEPAC-International) to simulate the average life expectancies and total health care costs (2006 US$) associated with different monitoring strategies to guide switching to 2nd-line ART. Monitoring strategies included clinical assessment, CD4 cell count, and HIV RNA testing, with criteria for 1st-line ART failure a single WHO stage III-IV event, 50% decrease in peak CD4, and return to baseline HIV RNA level, respectively. Time on failed 1st-line ART resulted in resistance mutations, which reduced 2nd-line ART efficacy. Data were derived from clinical trials and cohort studies from Côte d’Ivoire and published literature. Sensitivity analyses were conducted to explore the impact of uncertain parameters and assumptions, as well as to assess variations of the three main monitoring strategies.
Result: Compared with 1st-line ART only, the incremental benefits from the availability of 2nd-line ART ranged from a 23% (clinical monitoring) to a 39% (CD4 count) to a 48% (HIV RNA) increase in undiscounted life expectancy. The incremental cost-effectiveness ratio of switching to 2nd-line ART based on clinical monitoring was $1,750 per year of life saved (YLS) compared to 1st-line ART only; biannual CD4 monitoring was $2,300 per YLS. The incremental cost-effectiveness ratio of biannual HIV RNA testing ranged from $3,760 ($87/test) to $2,290/YLS ($25/test), compared to the next best strategy. While continued ART following virologic failure provided life-expectancy gains, the costs associated with never stopping ART were substantial. If 2nd-line ART costs were reduced, the cost-effectiveness of HIV RNA monitoring became more attractive. Results were also influenced by the impact of resistance on 2nd-line ART efficacy.
Conclusion: Use of simulation models to examine the costs and consequences of different laboratory monitoring strategies can assist in rational use of HIV treatment resources in settings like Côte d’Ivoire. Results can inform not only whether CD4 count and HIV RNA monitoring are used, but how they are implemented in clinical care.
Purpose: About half of all pregnancies in the US are unintended. Emergency contraceptive pills are 89 percent effective in preventing pregnancy if taken within 72 hours of unprotected sex. In August 2006, the FDA announced that Plan B, commonly referred to as the “morning after pill”, would be made over-the-counter (OTC) for women 18 and older. Women age 17 and under would still require a prescription from a physician. Prior to the legislation, nine states had pharmacy access legislation allowing a woman of any age to purchase Plan B from a pharmacist. This study assess whether by increasing access to Plan B, we observe a decrease in number of abortions and an increase in sexually transmitted infections (STIs). The latter would occur if increased access to Plan B increases the frequency of unprotected sex or causes women to abandon effective forms of birth control.
Method: Data source is the Thompson MarketScan Database 2005-2007 with sample size of 1,685,669 unique females ages 15-44 in each year. STIs and abortion identified using ICD-9 codes and CPT4 procedure or supplies codes provided in outpatient claims data. Using a pre-post design with an early adopter control group, I identify the effect of the FDA ruling on two outcomes of interest: STIs and abortion using a difference-in-difference estimator allowing for age trends. A log-link model and logit regression is specified and bootstrapped standard errors around the average marginal effect are obtained. Cost-effectiveness analysis is used to compare medical costs across alternatives: physician visit (time and monetary) and prescription cost, retail cost of OTC pill, and abortion in the event of unintended pregnancy.
Result: Making Plan B OTC resulted in 416 additional STIs per 100,000 women age 15-44, 95% CI [258, 575] and 108 fewer abortions per 100,000 women age 15-29, 95% CI [54, 171]. The relative risk of STI among women in early adapter states compared to those in late adapter states is 1.045, 95% CI [10.014, 1077]. Women 15-29 in the early adopter states have a RR of abortion over the laggard states of 0.898, 95% CI [0.827, 0.976].
Conclusion: Physicians should counsel women on safer sex practices and pharmacists could offer information on safer sex practices with purchase of Plan B.
Purpose: Invasive cervical cancer is the most frequent cause of cancer death among women in
Method: Model calibration was conducted using a likelihood-based approach, fitting model outcomes to country- and region-specific epidemiologic data (e.g., age-specific prevalence of HPV and precancerous lesions, HPV type-distribution, and cervical cancer incidence). Face validity of the model was assessed using primary data collected from women in rural
Result: Assuming complete protection against HPV-16,-18 in girls previously unexposed, the mean reduction in lifetime cancer risk was 30% (range 26.4%-39%) with a school-based vaccination program reaching 90% of primary school enrollees (~56% enrollment at age 9). If this strategy included rapid HPV testing in adulthood, reductions would increase to 43% with 25% screening coverage, and 52% with 50% screening coverage. For older girls, vaccine efficacy is likely to be reduced as girls increasingly will have been exposed to HPV infection and school enrollment rates rapidly decline. For example, with a 25% decline in efficacy and a 25% drop-off in school enrollment, vaccinating in the mid-teens would provide a mean reduction of 13.8%.
Conclusion: Even if attainable vaccination and screening coverage rates are low in
Purpose: To project and compare clinical outcomes of adjuvant radiation soon after radical prostatectomy for locally advanced prostate cancer vs. initial observation with salvage radiation delivered at early prostate specific antigen recurrence.
Methods: A state-transition Markov model was constructed to modify the published results of randomized studies of observation vs. adjuvant radiation such that the observation patients were given salvage radiation at early prostate specific antigen recurrence. Transition probabilities and utility inputs were drawn from randomized controlled trials of adjuvant radiation and cohort studies of salvage radiation and calibrated to validate the model against the reference articles. Outcomes of prostate specific antigen recurrence-free probability, metastasis-free survival, overall survival and projected quality-adjusted life expectancy were modeled through 10 years. Sensitivity analysis and probabilistic sensitivity analysis were performed.
Results: At 10 years, observation with early salvage radiation yields similar results compared to adjuvant radiation for the outcomes of freedom from prostate specific antigen recurrence (53% and 52%, respectively), metastasis-free survival (72% and 70%, respectively) and overall survival (74% and 74%, respectively). Findings were robust to sensitivity analyses and probabilistic sensitivity analyses. After adjusting for the disutility of radiation therapy, observation with early salvage radiation was slightly superior to adjuvant radiation through 10 years (7.0 and 6.2 quality-adjusted life years, respectively).
Conclusion: This decision analysis model suggests that for patients with locally advanced prostate cancer after radical prostatectomy, a strategy of initial observation with salvage radiation given at early prostate specific antigen recurrence yields cancer control and survival outcomes similar to adjuvant radiation while minimizing the morbidity of radiation.
Purpose: Method: Result: Conclusion:
Method: Result: Conclusion: