Olds 1999

Methods	RCT Length of follow‐up: 6 months for randomized comparison
Participants	All children living in endemic area Number analysed for primary outcome: 1518 randomized, 90% followed up at 6 months Age range/mean age: 10.5 years Inclusion criteria: school age children Exclusion criteria: failure to submit 2 stool specimens prior to the initial treatment, known allergy to either drug, treatment with either drug within 6 months, lack of consent, and marriage or possible pregnancy
Interventions	Single dose vs placebo Albendazole (400 mg) plus praziquantel (40 mg/kg) Praziquantel plus an albendazole placebo Albendazole plus a praziquantel placebo Both placebos
Outcomes	No useable data. Not included in review: ultrasound, physical examination and history findings, duplicate stool and urine measurements of egg counts Measured but not reported: weight, height, skinfold thickness (subscapular, triceps, and abdominal) and haemoglobin recorded at baseline and end point but only baseline data reported; data for side effects not useable in review
Notes	Location: China, Philippines and Kenya Community category: 1 randomized comparison up to 6 months at which point all infected children were treated as needed, and followed up until one year. There was no difference between the side effect rate from albendazole or the double placebo Result text: "No statistically significant improvement was seen in haemoglobin after albendazole treatment. In the trial population as a whole, no significant differences between treatment groups were seen in any of the growth and anthropometric measurements." Source of funding: Tropical Disease Research of the WHO.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Computer generated. "Randomization lists were prepared by WHO/TDR using a randomized block design with a block size of 80".
Allocation concealment (selection bias)	Low risk	Central allocation.
Blinding (performance bias and detection bias) All outcomes	Low risk	Participants, key personnel, and outcome assessment was blinded. "The randomization code was not broken until after the 6‐month results were tabulated and submitted to WHO".
Incomplete outcome data (attrition bias) All outcomes	Low risk	1518 participants, 90% at 6 months follow‐up, 83% at one year, no further details. Inclusion of all randomized participants (number evaluable/number randomized): 90% (1366/1518).
Selective reporting (reporting bias)	High risk	Weight, height, skinfold thickness, and haemoglobin recorded at baseline and end point but only baseline data reported.
Other bias	Low risk	No obvious other source of bias.