Table 2 A list of the candidate primary and secondary outcome measures, their metrics, and aggregation at the time point of measurement

Candidate primary outcome measure

Metric and aggregation as primary outcome measure

Time points

Perceptual ratings by blinded assessors of target consonants in treated and untreated wordlists

% target Consonants Correct (PCC)

t(−1), t7, t8 (baseline and both post-treatment assessments)

Perceptual ratings by blinded assessors of target consonants of within-treatment wordlists

% target Consonants Correct (PCC)

t1 to t6 (therapy)

Candidate secondary patient-reported outcome measures

Metric and aggregation as primary outcome measure

Time points

Patient-reported outcome measure Cleft-Q (functioning and distress subscales)

Standard score

t(−1), t7, t8 (baseline and both post-treatment assessments)

Patient-reported outcome measure ICS

Standard score

t(−1), t7, t8 (baseline and both post-treatment assessments)

Patient-reported experience measure

% positive, negative and neutral responses

t8 (1-month post-treatment)

Intervention acceptability questionnaire

% positive and negative responses

t8 (1-month post-treatment)