Small Area Mental Health Index (SAMHI)

Project Description

The Small Area Mental Health Index (SAMHI) is a freely available annual composite measure of population mental health status for every Lower Super Output Area (LSOA) in England, covering the period 2011-2022 across 32,844 small areas. Developed at the University of Liverpool and published on the PLDR platform, SAMHI provides a consistent longitudinal time series that enables researchers and public health practitioners to monitor mental health inequalities at neighbourhood level.

The index integrates four administrative data sources that together capture different dimensions of population mental health burden: NHS mental health hospital attendances, antidepressant prescribing rates (defined daily doses per 1,000 population, ADQ-weighted), QOF depression prevalence (GP-registered depression diagnoses), and DWP disability benefit claims for mental health conditions (DLA/PIP). Each indicator was standardised using z-scores and the combined index was derived via maximum likelihood factor analysis, which from version 4.00 onwards identified two underlying factors reflecting distinct components of mental health need.

Annual index values and decile rankings are produced for each LSOA, enabling both cross-sectional mapping and longitudinal tracking of change. The standardised methodology is fully documented in the indicator specification to support reproducibility and reuse. SAMHI has been used in research on the mental health impacts of austerity, the pandemic, and place-based health inequalities.

Skills Used

• R
• Factor Analysis
• Z-score Standardisation
• Small Area Analysis
• Index Construction
• NHS Administrative Data
• DWP Data Integration