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How can we objectively categorise partnership type? A novel classification of population survey data to inform epidemiological research and clinical practice
  1. C H Mercer1,
  2. K G Jones1,
  3. A M Johnson1,
  4. R Lewis2,3,
  5. K R Mitchell2,4,
  6. K Gravningen5,
  7. S Clifton1,
  8. C Tanton1,
  9. P Sonnenberg1,
  10. K Wellings2,
  11. J A Cassell6,
  12. C S Estcourt7,8
  1. 1Research Department of Infection and Population Health, Centre for Sexual Health and HIV Research, University College London, London, UK
  2. 2Department of Social and Environmental Health Research, Centre for Sexual and Reproductive Health Research, London School of Hygiene and Tropical Medicine, London, UK
  3. 3Department of Sociology, University of the Pacific, Stockton, USA
  4. 4MRC/CSO Social and Public Health Sciences Unit, Institute of Wellbeing, University of Glasgow, Glasgow, UK
  5. 5Department of Microbiology and Infection Control, University Hospital of North Norway, Tromsø, Norway
  6. 6Division of Primary Care and Public Health, Brighton and Sussex Medical School, University of Brighton, Brighton, UK
  7. 7Blizard Institute, Barts and the London School of Medicine and Dentistry, London, UK
  8. 8Barts Sexual Health Centre, St Bartholomew's Hospital, London, UK
  1. Correspondence to Dr C H Mercer, Research Department of Infection and Population Health, Centre for Sexual Health and HIV Research, University College London, 3rd Floor, Mortimer Market Centre London WC1E 6JB, UK; c.mercer{at}


Background Partnership type is a determinant of STI risk; yet, it is poorly and inconsistently recorded in clinical practice and research. We identify a novel, empirical-based categorisation of partnership type, and examine whether reporting STI diagnoses varies by the resulting typologies.

Methods Analyses of probability survey data collected from 15 162 people aged 16–74 who participated in Britain's third National Survey of Sexual Attitudes and Lifestyles were undertaken during 2010–2012. Computer-assisted self-interviews asked about participants' ≤3 most recent partners (N=14 322 partners/past year). Analysis of variance and regression tested for differences in partnership duration and perceived likelihood of sex again across 21 ‘partnership progression types’ (PPTs) derived from relationship status at first and most recent sex. Multivariable regression examined the association between reporting STI diagnoses and partnership type(s) net of age and reported partner numbers (all past year).

Results The 21 PPTs were grouped into four summary types: ‘cohabiting’, ‘now steady’, ‘casual’ and ‘ex-steady’ according to the average duration and likelihood of sex again. 11 combinations of these summary types accounted for 94.5% of all men; 13 combinations accounted for 96.9% of all women. Reporting STI diagnoses varied by partnership-type combination, including after adjusting for age and partner numbers, for example, adjusted OR: 6.03 (95% CI 2.01 to 18.1) for men with two ‘casual’ and one ‘now steady’ partners versus men with one ‘cohabiting’ partner.

Conclusions This typology provides an objective method for measuring partnership type and demonstrates its importance in understanding STI risk, net of partner numbers. Epidemiological research and clinical practice should use these methods and results to maximise individual and public health benefit.


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  • JAC is joint senior author.

  • Handling editor David A Lewis

  • Contributors The paper was conceived by CHM, CSE and JAC. CHM wrote the first draft, with further contributions from all authors. Statistical analyses were undertaken by KGJ and CHM. CHM, AMJ (principal investigator), PS and KW, initial applicants on Natsal-3, wrote the study protocol and obtained funding. Natsal-3 questionnaire design, ethics applications and piloting were undertaken by CT, SC, RL, KRM, CHM, AMJ, PS and KW. SC was responsible for data collection and delivery. Data management was undertaken by NatCen Social Research (SC), UCL (CT and CHM) and LSHTM (RL). All authors contributed to data interpretation, reviewed successive drafts and approved the final version of the manuscript.

  • Funding Medical Research Council [G0701757] and the Wellcome Trust [084840] with contributions from the Economic and Social Research Council and Department of Health.

  • Competing interests AMJ has been a Governor of the Wellcome Trust since 2011.

  • Ethics approval Oxfordshire Research Ethics Committee A.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement The Natsal-3 dataset is publicly available from the UK Data Service:; SN: 7799; persistent identifier: 10.5255/UKDA-SN-77991-1.

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