DEVTA (1999 - 2004; first results 2007):

The world's largest-ever randomised trial

2x2 cluster-randomised trial of De-worming and Enhanced Vitamin A (DEVTA) in one million rural children in the state of Uttar Pradesh (UP) in north India. Principal investigator: Dr Shally Awasthi, King George's Medical University, Lucknow, India.

Units of randomisation: 72 development blocks

  • 18 allocated 6-monthly vitamin A (200,000 IU)

  • 18 allocated 6-monthly de-worming (400mg albendazole)

  • 18 allocated both

  • 18 allocated neither

Study population within blocks: all the children aged up to 6 years in all the functioning pre-school (anganwadi) centres in the block; mean about 10-20,000 children per block, total (72 blocks) about 1 million children.

Intervention: once every 6 months for 5 years, select an intervention day and get the existing anganwadi workers to treat all then aged 6 months to 6 years.

Main outcome: mortality between ages 1.0 and 6.0.

Main analyses: compare 36 vs 36 cluster-specific results (72 data points only, and so of correspondingly limited sensitivity).

  • 36 vit A vs 36 no vit A blocks
  • 36 de-worming vs 36 no de-worming blocks

No significant interactions between the effects of the two treatments on major outcomes (so any analyses of 18 vs 18 blocks would be subsidiary analyses).