Table 1

Determinants of age of ADHD diagnosis

Regression estimate
(95% CI)		Effect sizeInterpretation
Characteristics of households within the practice
 Single parent (>18 years) householdsNot statistically significantNot statistically significant
 Average number of children in the household0.2759
(0.027774 to 0.524016)		27.59%For every unit increase in number of children in the household, there is on average 27.6% increase in ADHD diagnosis age within the practice
 Average age difference within the household0.03755
(−0.00109 to 0.0761898)		3.755%For every unit increase in age difference within practice households, there is 3.8% increase in ADHD diagnosis age within the practice
General practice characteristics
 General practice size0.00002938
(0.00000730 to 0.00005147)		0.002938%For every increase in the practice size by 100, there is on average 0.3% increase in ADHD diagnosis age in the practice
 Total number of children−0.0001045
(−0.0001954 to −0.0000136)		−0.001045%For every unit increase in the number of children in the practice by 100 there is on average 0.1% decrease in ADHD diagnosis age within the practice
 Proportion of eligible children—in lowest IMD quintileNot statistically significantNot statistically significant
 Mean years since medical qualification of GPsNot statistically significantNot statistically significant
 Mean number of specialist qualifications of GPsNot statistically significantNot statistically significant
 Urban/rural practiceNot statistically significantNot statistically significant
 QOF achieved in 2015–2016— overall (%)Not statistically significantNot statistically significant
 NHS choices star ratingNot statistically significantNot statistically significant
Characteristics of children with ADHD within the practice
 ADHD prevalence rateNot statistically significantNot statistically significant
 Hyperkinetic conduct disorder prevalence rateNot statistically significantNot statistically significant
  ADHD of non-white ethnicity within the practice (%)Not statistically significantNot statistically significant
 Female children with ADHD (%)Not statistically significantNot statistically significant

  • ADHD, attention deficit hyperactivity disorder;  GP, general practitioner; IMD, index of multiple deprivation; QOF, Quality and Outcomes Framework.