Background
The number of children and young people (CYP) diagnosed with mental health problems has increased over the past decade. The COVID-19 pandemic also has accelerated this increase, raising significant concerns about adolescent emotional wellbeing. Research suggests that adolescents who live in more deprived areas are more likely to experience poor emotional wellbeing. Children in the northwest of England are among those with the poorest outcomes in the UK. We aimed to investigate the association between deprivation and mental health outcomes from 2019 to 2022. The aim was to support local authorities with targeted provision of public health services as well as predicting service need for 2022 onwards.

Methods
In this cross-sectional study, we analysed routinely collected Schools Health Needs Assessment (SHNA) data. The School Health Needs Assessment dataset contained 32 676 responses from Year 6 (ages 10–11 years) and Year 9 (ages 13–14 years) who completed the annual survey in 2019–22. The questionnaire was offered to all mainstream schools, delivered by the public health school nursing service. Index of multiple deprivation (IMD) data were provided for household postcodes. Data were analysed using IBM SPSS. Factor analysis created a composite emotional wellbeing scale (EWS) and estimates generated by school year (Years 6 and 9) and three academic years (2019–22). We calculated correlations between IMD and EWS overall and within school and academic year samples.

Findings
The final total sample across the three consecutive survey years and the two school years was 32 659. The sample consisted of 15 932 (49%) female students and 5066 (16%) students who registered at school as from an ethnic minority. Of the total sample, 9209 (28%) lived in a postcode in the most deprived IMD quintile in England. There was an overall decrease in EWS from Year 6 to Year 9 and from 2019 to 2022. The Year 6 students in 2022 reported mean levels of EWS equivalent to Year 9 students in 2019 indicating a shift toward poorer mental health in younger children. The correlational analyses showed no significant associations between IMD and EWS scores within the school or academic year cohorts. A follow-up analysis of children in receipt or not in receipt of free school meals also showed no significant association with EWS scores.

Interpretation
Findings showed that the emotional wellbeing of children and young people in the northwest of England has deteriorated since 2019, with greatest changes observed in the younger cohort of children in Year 6. This was not explained by postcode-based indices of multiple deprivation. Although it is recognised that deprivation is both a cause and a result of poor mental health, policy decisions on service provision for children and young people should not be based solely on IMD or receipt of free school meals. A rapid response is required to address the decline in emotional wellbeing currently observed in younger children of the northwest of England.