UK LLC profile: updated April 2026

Last modified: 01 Apr 2026

Key demographic characteristics of LPS participants included in the UK LLC TRE.

Introduction

As explained on the UK LLC sample page, the number of Longitudinal Population Study (LPS) participants in the UK LLC Trusted Research Environment (TRE) changes over time. UK LLC manages this complexity by establishing a ‘data freeze’ of the pooled sample on a quarterly basis. Each freeze comprises a number of tables that summarise the basic characteristics of the UK LLC sample at that point in time, for example, how many participants from each LPS are included in the UK LLC TRE and how many are linked to each of the linked data sources. You can access each individual freeze under the UK LLC sample section.

Periodically, UK LLC produces a summary of the demographic characteristics of LPS participants in the UK LLC TRE, including their sex, gender, year of birth (as a proxy for age) and ethnic group. This information is drawn from two sources:

• Harmonised LPS demographic variables created by UK LLC.

• Demographic information provided by NHS England (NHSE).

The 'best measure' combination of LPS and NHSE data

For sex, gender and ethnicity, the best measure in the tables below was determined using a hierarchical approach for each LPS participant. Where available, the most recent LPS (self-reported) data was selected. When LPS data was not available, NHS England data was used for participants with linked NHS England records.
For year of birth, the same hierarchical approach, in which self-reported data take precedence over NHSE data, was initially used. However, for participants whose year of birth had to be calculated by UK LLC from the date of data collection, the year of birth provided by NHSE takes precedence in the derivation of the 'best measure' value.

Missing data

• All categories of missing data (e.g. ‘not answered’, ‘prefer not to say’) have been grouped together in these tables. Details about how missing data are treated in the UK LLC-managed harmonised datasets, are available from the Harmonised LPS demographic variables page.

• There is currently a high proportion of missing LPS data for these variables because the LPS data most recently ingested into the TRE has not yet been processed. This will be rectified in the next data freeze.

UK LLC profile (based on Freeze 15, February 2026)

Sex

All LPS collected sex assigned at birth.
For NHS England, sex was determined using the most recent record from the Personal Demographics Service.

	LPS data N (%)	NHSE data N (%)	‘Best measure’ N (%)
Male	123,745 (40.2%)	81,045 (33.9%)	143,700 (38.7%)
Female	184,406 (59.8%)	158,047 (66.1%)	227,322 (61.3%)
Total ‘known’	308,151	239,092	371,022
Missing (% total)	269,501 (46.7%)	506 (0.2%)	206,630 (35.8%)
Total sample	577,652	239,598	577,652

Gender

Six LPS collected information about participants’ gender.
NHS England does not provide any gender identification measures.

	LPS data N (%)	NHSE data N (%)	‘Best measure’ N (%)
Male	16,631 (26.7%)	n/a	16,631 (26.7%)
Female	44,794 (71.8%)	n/a	44,794 (71.8%)
Non-binary	697 (1.1%)	n/a	697 (1.1%)
Prefer to self-define	254 (0.4%)	n/a	254 (0.4%)
Total ‘known’	62,376	n/a	62,376
Missing	515,276 (89.2%)	n/a	515,276 (89.2%)
Total sample	577,652	n/a	577,652

Year of birth

	LPS data N (%)	NHSE data N (%)	‘Best measure’ N (%)
Pre-1935	7,661 (2.3%)	6,080 (2.5%)	7,702 (2.0%)
1936-1945	16,688 (5.1%)	12,488 (5.2%)	17,286 (4.6%)
1946-1955	45,255 (13.8%)	30,644 (12.8%)	47,710 (12.6%)
1956-1965	65,675 (20.0%)	36,048 (15.0%)	70,416 (18.7%)
1966-1975	75,548 (23.0%))	41,258 (17.2%)	81,952 (21.7%)
1976-1985	47,406 (14.4%)	30,983 (12.9%)	54,176 (14.4%)
1986-1995	43,626 (13.3%))	42,917 (17.9%)	55,468 (14.7%)
1996-2005	13,456 (4.1%)	25,786 (10.8%)	29,242 (7.7%)
2006-2015	13,400 (4.1%)	13,394 (5.6%)	13,495 (3.6%)
Total ‘known’	328,715	239,598	377,477
Missing	248,937 (43.1%)	n/a	200,205 (34.7%)
Total sample	577,652	239,598	577,652

Ethnic group (6 categories)

Ethnicity was collected by most LPS, but to varying degrees of granularity. UK LLC has harmonised LPS data on ethnicity into six, five and two categories to include all LPS that collected these data. Only the most and least granular categories are presented here.

For NHS England, a hierarchy of source reliability established by the British Heart Foundation Data Science Centre was used (https://www.bmj.com/content/373/bmj.n826). Where multiple entries existed from the preferred source, the most recent was given precedence.

	LPS data N (%)	NHSE data N (%)	‘Best measure’ N (%)
White	138,212 (81.3%)	176,568 (87.3%)	246,166 (86.7%)
Black	3,643 (2.1%)	2,516 (1.2%)	4,651 (1.6%)
South Asian	20,760 (12.2%)	16,878 (8.3%)	22,528 (7.9%)
Other Asian	2,863 (1.7%)	1,700 (0.8%)	3,534 (1.2%)
Mixed	3,162 (1.9%)	2,603 (1.3%)	4,640 (1.6%)
Other	1,379 (0.8%)	2,048 (1.0%)	2,382 (0.8%)
Total ‘known’	170,019	202,313	283,901
Missing	407,633 (70.6%)	37,285 (15.6%)	293,751 (50.9%)
Total sample	577,652	239,598	577,652

Ethnic group (2 categories)

	LPS data N (%)	NHSE data N (%)	‘Best measure’ N (%)
White	230,924 (86.2%)	176,568 (87.3%)	277,843 (87.5%)
All other ethnic groups	36,918 (13.8%)	25,745 (12.7%)	39,854 (12.5%)
Total ‘known’	267,842	202,313	317,697
Missing	309,810 (53.6%)	37,285 (15.6%)	259,955 (45.0%)
Total sample	577,652	239,598	577,652

The last full-cohort profile available on Guidebook was based on Freeze 11 (February 2025).
This has been archived here.