A Systematic Review Assessing the Economic Impact of Sildenafil Citrate (Viagra®) in the Treatment of Erectile Dysfunction
Bibliographic record
Abstract
INTRODUCTION: Sildenafil was the first oral phosphodiesterase type 5 (PDE5) inhibitor introduced as primary therapy for erectile dysfunction (ED). In the 7 years following its market launch, sildenafil was prescribed by more than 750,000 physicians to more than 23 million men worldwide. To date, few studies have evaluated the economic impact of sildenafil in treating ED. AIM: To evaluate the cost-effectiveness and impact of sildenafil on health care costs for patients with ED in multiple countries. MAIN OUTCOMES MEASURES: Economic outcomes including cost, cost-effectiveness, cost of illness, cost consequence, resource use, productivity, work loss, and willingness to pay (WTP) were investigated. METHODS: Using keywords related to economic outcomes and sildenafil, we systematically searched literature published between July 2001 and July 2011 using MEDLINE and EMBASE. Included articles pertained to costs, WTP, and economic evaluations. RESULTS: In the last 10 years, 12 studies assessed economic outcomes associated with sildenafil for ED. Most studies were conducted in the United States and the United Kingdom, with one study identified in Canada and one from Mexico. Six studies evaluated cost of illness, cost consequence, or cost of care, and four studies evaluated WTP or drug pricing by country in the United States and the United Kingdom. In the United States and the United Kingdom, costs to health care systems have increased with demand for treatment. Cost analyses suggested that sildenafil would lower direct costs compared with other PDE5 inhibitors. U.S. and U.K. studies found that patients exhibited WTP for sildenafil. The two cost-effectiveness models we identified examined ED sub-groups, those with spinal cord injury and those with diabetes or hypertension. These models indicated favorable cost-effectiveness profiles for sildenafil compared with other active-treatment options in both Mexico and Canada. CONCLUSIONS: The relative value of sildenafil vs. surgically implanted prosthetic devices and other PDE5 inhibitors, is underscored by patients' WTP, and cost-effectiveness in ED patients with comorbidities.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.008 | 0.048 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.008 | 0.007 |
| Bibliometrics | 0.011 | 0.014 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.003 | 0.002 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.001 |
| Insufficient payload (model declined to judge) | 0.007 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".