Cohort Summary Statistics

The Basics

The Airwave Tissue Bank is an epidemiological study of police officers and staff in Britain. It is managed and run by the Department of Epidemiology & Biostatistics at Imperial College London, and we believe it to be the only large-scale cohort study of police employees anywhere in the world.

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The cohort has been richly phenotyped, flagged to routine records, and has a substantial biobank of blood and urine samples. It provides an excellent and unique resource to study the genetic, metabolic, occupational and lifestyle factors associated with mental health and cognitive performance among a predominantly male and young adult workforce with a well-defined organisational hierarchy.

The cohort was established in 2004 to investigate possible long-term health effects associated with use of TETRA, the radio system used by the police service. Mean age at recruitment was 39.8 y (σ = 16.0) and ranged from 16 - 80 y. The mean duration of follow-up at January 2025 is 15.2 y (σ = 2.9). It includes a group – younger men aged between twenty and forty years – who are particularly under-represented in the UK research portfolio, who have proven hard to engage in primary prevention, and have least routine contact with primary care. Some further statistics on the cohort are set out in the table below.

Recruitment was completed in 2015, and over the next four years a series of papers were published to evaluate the effect of TETRA on health. Whilst our overall assessment was that insufficient time has passed to form any final conclusions, we continue to follow-up the cohort through national registers, via follow-up screening and self-administered surveys.

We have also successfully re-purposed the cohort to support broader research goals into common diseases affecting this well-defined occupational group. For example, the cohort made a significant contribution to COVID-19 research, by providing 5985 volunteers for studies into novel methods for diagnosis of SARS-CoV-2 infection. We are core members of Dementia Platform UK (DPUK), UK Longitudinal Linkage Collaboration, and are listed on eight other directories supporting researchers worldwide.

Researchers can apply to our Access Committee for access to samples and data in order to carry out their own research projects. As members of the DPUK public-private partnership, researchers can build a virtual cohort of participants from the many cohorts registered with DPUK. Participants can be selected from their genotype and / or phenotype, and participants may be invited to join researchers' own projects or clinical trials.

Summary of Assets

Asset

N (participants)

Participants, net of withdrawals

53,244

Clinic-based measurements – baseline

45,594

Clinic-based measurements – follow-up

18,317

Cognitive first assessment

37,122

Cognitive follow-up assessment

11,489

7-day food diaries – baseline

23,388

7-day food diaries – follow-up

11,626

Sickness absence (HR departments)

32,102

Estimated TETRA usage

48,518

ECGs – baseline

45,381

ECGs – follow-up

15,832

GWAS

20,193

Exome array

1,947

Methylation array

920

Metabolomics (NMR, mass spectrometry)

6,242

Blood, urine & DNA samples

45,655

Proteomics

4,972

Biological Samples

When participants attend clinics, we generally collect a sample of blood and urine in a variety of collection tubes. Following biochemistry and haematology assays, which are carried out generally within 24-hours, we store the remaining material in cryogenic conditions for more detailed assays at a later date. These have included genetic and metabolomic assays, with proteomics planned.

The following is a summary of the biological material available according to our inventories as of March 2026. We are currently conducting a stock-take and rationalization of the collection and the numbers presented here will change over the course of 2026. If you are interested in making use of the samples, please contact us.

Collection TubeMaterialAliquotsBaselineFollow-UpParticipantsBoxesCollected FromCollected Till
ACDLymphocytes107,216 30,870 6,936 32,579 790 Aug 2008Mar 2020
CardDry Blood Spot5,114 5,112 5,112 80 May 2012Jul 2020
EDTADNA38,240 20,424 100 20,366 476 Jul 2006Nov 2016
 Plasma123,696 44,889 21,844 45,045 13,515 Jul 2004Aug 2023
 Red Blood Cells92,426 34,339 16,158 37,194 9,458 Jul 2004Feb 2021
 White Blood Cells46,646 25,120 20,972 33,687 9,958 Jul 2004Feb 2021
 Whole Blood7,188 -   1,520 1,520 288 Jan 2021Aug 2023
Lithium HeparinPlasma106,884 43,074 15,897 43,155 12,311 Jul 2004Aug 2023
 Red Blood Cells39,721 16,626 -   16,273 3,469 Jul 2004Nov 2009
 White Blood Cells36,392 32,998 32,410 6,996 Jul 2004Jul 2016
SwabNasal Mucus5,173 -   5,173 5,172 Jun 2020Jul 2020
Sodium CitratePlasma47,703 43,963 43,134 9,233 Jul 2004Jul 2016
 Red Blood Cells19,976 16,656 -   16,301 3,481 Jul 2004Nov 2009
 White Blood Cells47,164 43,547 -   42,740 9,161 Jul 2004Mar 2015
SSTSerum194,524 44,850 21,916 44,458 12,454 Jul 2004Aug 2023
Salivabio KitSaliva787 -   784 784 10 Jan 2021Feb 2021
Tempus TubeRNA281 156 161 Dec 2006Feb 2020
 Whole Blood50,065 4,701 21,77122,3273,265Nov 2012Aug 2023
PotUrine190,352 41,277 14,359 41,377 10,864 Jul 2004Aug 2023

Descriptive Statistics

In the tables below, participants with no information on gender (N=17) are excluded. Means (SD) are presented for age and percentages are presented for all other variables; n refers to the number of participants for whom each variable is available.

Means (SD) and percentages are presented for continuous and categorical variables respectively; n refers to the number of participants for whom each variable is available. The following definitions apply:

  • SBP: systolic blood pressure.
  • DBP: diastolic blood pressure.
  • HbA1c: glycosylated haemoglobin.
  • GCSE: General Certificate of Secondary Education (usually taken at 16-years)
  • Hypertension is defined as systolic blood pressure > 140 mmHg or diastolic blood pressure > 90 mmHg.

Demographics

MetricWomenMenTotal
N (%)19,567 (36.8)33,661 (63.3)53,228
Age (years) (n = 53,167)38.5 (9.4)40.6 (8.9)39.8 (9.1)
Marital status (%) (n = 40,889)   
Married46.768.660.5
Cohabiting20.815.117.2
Single18.77.811.9
Divorced/separated10.36.88.1
Other3.41.72.3
White (n = 38,725)9594.694.8
Black (n = 441)1.50.81.1
South Asian (n = 547)1.31.41.3
Mixed (n = 454)1.11.11.1
Other (n = 699)1.121.7
Education (%) (n = 40,889)   
Left school before taking GCSEs3.343.8
GCSE or equivalent27.631.129.8
Vocational qualification7.177
A-levels or equivalent31.132.131.7
Bachelor degree or equivalent23.120.121.2
Postgraduate qualifications7.95.76.5
Rank (%) (n = 37,251)   
Police staff47.516.427.9
Police Constable/Sergeant46.67262.6
Inspector/Chief Inspector3.3107.5
Other2.71.62
Smoking status (%) (n = 41,345)   
Non-smoker65.268.567.3
Past smoker22.72322.9
Current smoker12.18.59.8

Age-Sex Distribution at Baseline

Mean age at recruitment was 39.8 (s.d. 9.1; range 16 to 80) years; mean duration of follow-up to date is 13.8 (s.d. 2.9) years.

Age-

Ethnicity and Location

For those with ethnicity data, 94.8% self-report as white, 1.3% South Asian, 1.1% Black, 1.1% mixed ethnicity, 1.7% other, reflecting the demography of the police force at that time. 70% of the cohort were recruited in England, 15% in Scotland and 15% in Wales.

Clinical and Biological Measurements

MetricWomenMenTotal
N (%)17,059 (36.9%)29,165 (63.1%)46,224
BMI (kg/m2) (n = 45,471)26.0 (4.7)28.0 (3.7)27.2 (4.2)
BMI < 25 kg/m2 (%)49.320.531.1
25 kg/m2 < BMI < 30 kg/m2 (%)33.854.446.8
BMI > 30 kg/m2 (%)16.925.122.1
SBP (mmHg) (n = 45,483) 122.2 (14.1)134.8 (13.7)130.1 (15.1)
DBP (mmHg) (n = 45,483)76.1 (9.5)81.2 (9.9)79.3 (10.1)
Hypertension12.934.926.8
Total cholesterol (mmol/l) (n = 45,186)5.1 (1.0)5.4 (1.1)5.3 (1.0)
Total cholesterol > 5 mmol/l53.564.760.6
HbA1c % (n = 45,019)5.6 (0.6)5.6 (0.6)5.6 (0.6)
HbA1c % < 6 (%)81.285.583.9
6 < HbA1c % < 6.5 (%)14.911.412.7
HbA1c % > 6.5 (%)3.93.13.4
Self-reported diabetes diagnosis (n = 41,100) (%)0.810.9

Education, Marital Status, Rank & Smoking

The graph below is for men and women across categories by education, marital status, rank and smoking among participants who attended a clinic visit at baseline.

Education, Marital Status, Rank & Smoking

Intervals Between Follow-up Screening Visits

The following table shows some descriptive statistics on the intervals (years) between successive follow-up screens.

VisitShortestMedianLongestMeanStd Dev.N
20.038.0317.638.083.4718,261
30.073.8915.843.652.433,323
40.041.7810.672.131.80434
50.260.644.481.411.3941
60.610.610.610.61-1