A randomised controlled trial comparing palate surgery at 6 months versus 12 months of age (the TOPS trial): a statistical analysis plan

BACKGROUND: Cleft palate is among the most common birth abnormalities. The success of primary surgery in the early months of life is crucial for successful feeding, hearing, dental development, and facial growth. Over recent decades, age at palatal surgery in infancy has reduced. The Timing Of Primary Surgery for cleft palate (TOPS) trial aims to determine whether, in infants with cleft palate, it is better to perform primary surgery at age 6 or 12 months (corrected for gestational age). METHODS/DESIGN: The TOPS trial is an international, two-arm, parallel group, randomised controlled trial. The primary outcome is insufficient velopharyngeal function at 5 years of age. Secondary outcomes, measured at 12 months, 3 years, and 5 years of age, include measures of speech development, safety of the procedure, hearing level, middle ear function, dentofacial development, and growth. The analysis approaches for primary and secondary outcomes are described here, as are the descriptive statistics which will be reported. The TOPS protocol has been published previously. DISCUSSION: This paper provides details of the planned statistical analyses for the TOPS trial and will reduce the risk of outcome reporting bias and data-driven results. TRIAL REGISTRATION: ClinicalTrials.gov NCT00993551. Registered on 9 October 2009. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13063-020-04886-y.