2015/16 to 2024/25 Annual summary statistics
Date of notice: 23 January 2026
Overview
We have identified an error in the way that we have calculated patient ages for a calendar year. This error has resulted in an overestimate of the number of patients in age-based analyses. Several tables in the supporting calendar year data are impacted, but there are no changes to the key findings, financial year data, or quarterly data.
Description of error
An error has been identified in the calculation of patient age for a calendar year.
Each prescription record was assigned an age based on the patient’s age as of 30 September in the financial year when the prescription was issued. Due to this approach, some patients were assigned 2 different ages in prescription records from the same calendar year.
When prescription records were later grouped by calendar year and age, these patients were counted twice.
Scope
The error directly affected the following tables in the calendar year supporting summary tables:
• Age_Band
• Age_Band_Category
• Age_Band_Gender
• Age_Band_Gender_Category
To fix the error, we reloaded the data from the NHSBSA Enterprise Data Warehouse. Because gender is a live variable and only a patient’s most recent gender is available, a patient’s recorded gender may have changed between the original publication in July 2025 and the reload in January 2026.
Therefore, the ‘Gender’ and ‘Gender_Category’ tables in the calendar year supporting summary tables have also changed.
Solution
Corrected versions of these tables have been produced by calculating ages based on 30 June of the calendar year when the prescription was issued, assigning a single age to each patient for the time period.
Impacts
Age_Band and Age_Band_Category tables
The number of identified patients has decreased across all known age bands compared to the previous version:
• an 8.9% decrease in the Age_Band table
• an 8.5% decrease in the Age_Band_Category table
The distribution of the number of items and Net Ingredient Costs have changed across age bands, but the total items and total Net Ingredient Costs have remained the same for both tables.
Age_Band_Gender and Age_Band_Gender_Category tables
The number of identified patients has also decreased across all known age band and gender groups, in line with the changes to the Age_Band and Age_Band_Category tables. These tables only include patients where gender and age are known, therefore the total items and total Net Ingredient Costs have changed where a patient’s gender has been updated.
Gender and Gender_Category tables
The distribution of identified patients, number of items, and Net Ingredient Costs has changed due to gender being a live variable in the NHSBSA Enterprise Data Warehouse. However, the total number of identified patients, the total number of items, and the total Net Ingredient Costs have not changed.
There is no change to the key findings, narratives, financial year data or quarterly data included in this release.
We apologise for any inconvenience caused.