| Methods |
Randomized controlled trial using randomly generated numbers. Allocation concealment by opaque, sealed envelopes. Outcome evaluator blinded. Participant blinding unclear. Few men lost to follow up or excluded following randomization. Participants with protocol violations, random allocation errors or technical failure were included in the primary analysis. |
| Participants |
1429 participants at 8 sites in 5 countries (Brazil, Guatemala, Indonesia, Sri Lanka, Thailand) from March 1988 to August 1991. The age range was not stated. Inclusion criteria were men in good health requesting vasectomy who were 21 years of age or greater. Some local eligibility criteria applied, such as in the Brazil site men were 30 to 40 years of age, had 2 live children, an 8th grade education and minimum monthly income, while Sri Lanka participants had to have 2 or more living children. Exclusion criteria included a history of excessive pain or swelling, abnormality or congenital anomaly and previous injury to or operation on the scrotum or testes, including any previous sterilization. |
| Interventions |
Vasectomy (small segment of the vas excised and ligated both ends) using a no‐scalpel incision (N=715) versus vasectomy (same technique) with a single or double vertical incision (N=714). Method of anesthesia was not stated. |
| Outcomes |
The primary outcome measure was safety. Secondary measures were ease of use, duration of procedure and effectiveness (sterility). Participants were to return between 3 and 15 days for post‐operative evaluation and at 10 weeks for semen analysis. Absence of live spermatozoa was considered proof of sterility. Failures were determined at surgeon discretion and criteria were not standardized among centers. Participants were encouraged to return whenever they had a problem related to surgery and until semen analysis showed no live spermatozoa or sterilization was declared. |
| Notes |
All 8 operators (general surgeons and urologists) had experience with the standard vasectomy technique while 3 had experience with the no‐scalpel technique.
Inexperienced surgeons were trained in the no‐scalpel technique before the study.
Analysis was not according to intent‐to‐treat principle since groups were based on treatment received (and not randomly‐assigned vasectomy method). The authors report a posteriori sample size calculation that had low power (65%) to detect a 3% difference in effect rates between the two groups at the 5% alpha level. |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Allocation concealment (selection bias) |
Low risk |
A ‐ Adequate |
