Appendix: Methods

Practice level data

  1. We took our data on primary care workforce from NHS digital General Practice Workforce data series. This data series is published monthly and includes practice level workforce headcount and full-time equivalent numbers by staff group. We used workforce data from September each year to capture the state of the workforce in the middle of each financial year.
  2. The NHS Digital General Practice Workforce data series also includes attribution data, mapping which neighbourhoods the patients registered with each practice live in.
  3. Appointments data were taken from the NHS Digital Appointments in General Practice data series. These data are provided daily at CCG level. We aggregated these data into quarters to reduce noise in the data, and report quarterly average appointment rates per 100 of population.
  4. QOF data were taken from the NHS Digital Quality and Outcomes Framework Achievement data.
  5. CQC overall ratings were taken from the most recent rating given to each practice.
  6. General practice patient satisfaction scores were taken from the GP patient survey, an independent survey run by Ipsos MORI on behalf of NHS England.
  7. Data on the finances of GP practices were taken from the NHS Digital NHS Payments to General Practice data series.

Our workforce data cover the financial years 2015/16 through 2018/19 – during this period there were a small number of GP practices that had workforce data missing for one or more years. For these practices we imputed workforce numbers from years where data were reported to estimate the workforce numbers for years where these data were missing using simple linear interpolation.

Neighbourhood level data

Our analysis examines how the primary care supply variables listed vary across different types of neighbourhood. The measure of neighbourhood we used is the lower-layer super output area (LSOA). This is a standard geographical measure defined in the 2011 census, which divided England into 32,844 LSOAs each with an average of approximately 1,500 residents or 650 households. We combined our primary care supply variables with the following data characterising neighbourhoods.

  1. We used neighbourhood level population data from ONS LSOA population estimates. These provide mid-year population estimates for each neighbourhood in the country broken down by age and sex.
  2. We used the 2019 version of the index of multiple deprivation (IMD 2019) from the Ministry of Housing, Communities and Local Government to attribute deprivation rankings to each neighbourhood in England. The IMD 2019 measure deprivation using a weighted average of seven dimensions – income (22.5%), employment (22.5%), education (13.5%), health (13.5%), crime (9.3%), barriers to housing and services (9.3%), and living environment (9.3%). Each dimension is constructed from a range of sub-indicators that together provide a rich picture of life in the neighbourhood. We rank neighbourhoods by their overall IMD score calculated by combining the seven dimensions and group neighbourhoods into groups of roughly equal populations representing deprivation quintile groups.

Population need adjustment

Populations in different neighbourhoods have different needs for primary care due to the different demographic structures of the neighbourhood, as well as the general level of ill health in the neighbourhood. In order to capture these different needs we applied weights to the population of each neighbourhood to construct a need adjusted population. The weights we use are those suggested by the most recent workload adjustment estimates produced by the 2007 Review of the General Medical Services global sum formula published by the British Medical Association and NHS Employers. These weight older patients and those living in neighbourhoods with worse health indicators (as captured by the health indicators that comprise the IMD health domain) and those who recently registered with a practice as having higher health care needs than younger patients and those living in neighbourhoods with better health indicators. We were unable to apply the registration status weights suggested by the report in our analysis as we did not have access to individual patient level data. The weights used are given in the table that follows.

Age-sex weight

Registration status weight

IMD health domain

Band

Weight

Band

Weight

Weight

Male 0–4 years

2.354

Registered with practice for 12 months+

1.000

The weight is calculated as:

1.054 to the power of the IMD health domain score associated with the patient’s postcode

Male 5–14 years

1.000

Male 15–44 years

0.913

Male 45–64 years

1.373

Male 65–74 years

2.531

Male 75–84 years

3.254

Male 85+ years

3.193

Female 0–4 years

2.241

Registered with practice in the past 12 months

1.689

Female 5–14 years

1.030

Female 15–44 years

1.885

Female 45–64 years

2.115

Female 65–74 years

2.820

Female 75–84 years

3.301

Female 85+ years

3.090

Having applied these weights, we derived need adjusted populations for each neighbourhood. Where neighbourhoods had characteristics that predict higher health needs, we inflated their populations to be larger than their actual population. Those with characteristics that predict lower health needs had their populations deflated to be smaller than their actual population. The total need adjusted population across all neighbourhoods is normalised to equal the pre-adjusted total population.

Analysis

Indicators were constructed either at neighbourhood (workforce, QOF and GPPS), GP practice (finance, practice size and CQC ratings) or CCG (appointments) level depending on data availability.

For neighbourhood level indicators we attributed each of the datasets from practice level to neighbourhood level in accordance with the proportions of patients served by each practice in each neighbourhood, as given in the attribution dataset. For example, if we had a practice with five GPs serving equal numbers of patients from 50 different neighbourhoods, we allocated 0.1 GPs from this practice to each neighbourhood. We did this for all practices and neighbourhoods allocating GPs in accordance with the proportion of the practice population of each practice living in each neighbourhood to get an estimate of how many GPs from across the different practices served the population in each neighbourhood overall. We then aggregated each of our primary care variables attributed to neighbourhood level into their respective neighbourhood deprivation quintile groups – these form the numerators for the indicators that we report in our analysis. We also attribute need adjusted neighbourhood populations into their respective neighbourhood deprivation quintile groups – these form the denominators of the indicators that we report in our analysis.

For practice and CCG level indicators, we instead attribute IMD scores and need adjusted population data from neighbourhoods to practices and CCGs in accordance with the proportion of each neighbourhood served by a practice or CCG respectively.

Our financing indicators are a little different from others as we use populations as reported by the practices in their registered lists of patients and weighted populations calculated by NHS England based on these lists of registered patients. We do this because these numbers form the basis of the actual funding allocation. We do not use these population numbers as the basis of our other indicators as they are not an entirely accurate reflection of the actual population – with people who have died or migrated from areas often remaining on GP practice registration lists.

Our analysis then compares how the different aspects of primary care supply, adjusted for differing population needs for primary care, are allocated across the deprivation quintile groups. If the need adjustment appropriately predicts differences in need between neighbourhoods, then once we adjust for need, we can test to see if the NHS meets its core objective of allocating health care according to need. Any disparities observed between the deprivation quintile groups suggests a systematic patterning of access to primary care by deprivation – this breaches the core NHS objective of equal access to health care for equal need.

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