# UK LLC profile: updated April 2026
>Last modified: 01 Apr 2026
<div style="background-color: rgba(0, 178, 169, 0.3); padding: 5px; border-radius: 5px;"><strong>Key demographic characteristics of LPS participants included in the UK LLC TRE.</strong></div>  

## Introduction  
As explained on the [**UK LLC sample page**](../sample/ukllc_sample.md), 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](../../ukllc_key_facts/sample/ukllc_sample.md). 

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**](../../ukllc_managed_data/datasets/sociodemo_harmonised/sociodemo_harmonised.md) created by UK LLC.
* [**Demographic information**](../../linked_health_data/nhs_england/registration_datasets/demographics/demographics.ipynb) provided by NHS England (NHSE).



<aside class="admonition note"><p class="admonition-title">The 'best measure' combination of LPS and NHSE data</p>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.<br>  
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.</aside> 

<br>

**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](../../ukllc_managed_data/datasets/sociodemo_harmonised/sociodemo_harmonised.md) 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](../sample/freezes/freeze15.ipynb), February 2026)
<div style="background-color: rgba(255, 218, 185, 0.5); padding: 5px; border-radius: 5px;"><strong>Sex</strong></div>  

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 |
| <i>Missing (% total) | <i>269,501 (46.7%) | <i>506 (0.2%) | <i>206,630 (35.8%) | 
| <b>Total sample | <b>577,652 |<b>239,598 |<b>577,652 |

<br>
<div style="background-color: rgba(255, 218, 185, 0.5); padding: 5px; border-radius: 5px;"><strong>Gender</strong></div>  

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 |
| <i>Missing | <i>515,276 (89.2%) | <i>n/a | <i>515,276 (89.2%) |
| <b>Total sample | <b>577,652 |<b>n/a | <b>577,652 |

<br>
<div style="background-color: rgba(255, 218, 185, 0.5); padding: 5px; border-radius: 5px;"><strong>Year of birth</strong></div>  
<br>

| | 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 |
| <i>Missing |<i>248,937 (43.1%) | <i>n/a | <i>200,205 (34.7%) |
| <b>Total sample | <b>577,652 |<b>239,598 |<b>577,652 |

<br>
<div style="background-color: rgba(255, 218, 185, 0.5); padding: 5px; border-radius: 5px;"><strong>Ethnic group (6 categories)</strong></div>  

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 |
| <i>Missing | <i>407,633 (70.6%) | <i>37,285 (15.6%) | <i>293,751 (50.9%)
| <b>Total sample | <b>577,652 |<b>239,598 |<b>577,652 |

<br>
<div style="background-color: rgba(255, 218, 185, 0.5); padding: 5px; border-radius: 5px;"><strong>Ethnic group (2 categories)</strong></div>  
<br>  

| | 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 |
| <i>Missing | <i>309,810 (53.6%) | <I>37,285 (15.6%) | <I>259,955 (45.0%) |
| <b>Total sample | <b>577,652 |<b>239,598 |<b>577,652 |  

<br>

>**The last full-cohort profile available on Guidebook was based on Freeze 11 (February 2025).  
> This has been archived [here](../profile/profile_freeze11.md).**