Kumamoto 1988.
| Methods | Randomised double‐blind parallel trial Duration of study: from January 1985 to June 1986 |
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| Participants | Country: Japan, 25 centres Population: men with abnormal sperm count or motility, N = 375 Mean age: unclear, average 32.8 (SD 4.8) years Inclusion criteria: average sperm count ≤ 40 × 106 /mL measured on ≥ 2 occasions OR average sperm count ≥ 40 count ≤ 40 × 106 /mL measured on ≥ 2 occasions AND sperm motility < 50% Exclusion criteria: sperm count only measured at 1 occasion, average sperm count ≤ 2 × 106/mL, sperm motility = 0%, testicular size < 8 mL using orchidometer bilaterally, use of hormone or anti‐hormone drug within preceding 3 months before the study period, WBC > 5/HPF in the semen or the presence of possible genito‐urinary infection, presence of hypoganadism or endocrine disease, presence of undescended testes, genito‐uninary tract obstruction, varicocele or any other serious associated condition also included concomitant use of anti‐hormonal and hormonal treatment and the 2 patients with polypharmacy were excluded from the data analysis |
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| Interventions | Mecobalamin (vitamin B12) 6.000 mcg (n = 125) versus Mecobalamin (vitamin B12) 1.500 mcg (n = 124) versus Placebo (n = 126) Duration of treatment: 12 weeks |
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| Outcomes | Sperm concentration, sperm motility | |
| Notes | Article in Japanese, translated by Dr Tomoko Kumaga and Tan Wantao. No contact details available for authors. No useable data available. |
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| Risk of bias | ||
| Bias | Authors' judgement | Support for judgement |
| Random sequence generation (selection bias) | Unclear risk | Quote: "The 396 patients were divided into 3 groups (6000ug/day, 1500ug/day, placebo) by randomisation. The implementation of randomisation and allocation concealment was carried out by two people (Doctor Yamamoto, Doctor Shimizu) |
| Allocation concealment (selection bias) | Unclear risk | See above |
| Blinding of participants and personnel (performance bias) All outcomes | Low risk | Quote: "Double blind". Placebo used. |
| Blinding of outcome assessment (detection bias) All outcomes | Unclear risk | Not mentioned |
| Incomplete outcome data (attrition bias) All outcomes | Unclear risk | No ITT. 21 lost to follow‐up; 19 dropouts, 2 polypharmacy 2018 Change in RoB to unclear. Not sure in which groups dropouts belonged. |
| Selective reporting (reporting bias) | High risk | Subgroup analysis performed as an addition post‐treatment |