title: How can we objectively categorise partnership type? A novel classification of population survey data to inform epidemiological research and clinical practice.
abstract: 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.
  
  
  
  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).
  
  
  
  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.
  
  
  
  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.
authors.affiliation: Research Department of Infection and Population Health, Centre for Sexual Health and HIV Research, University College London, London, UK.
authors.forename: C H
authors.initials: CH
authors.lastname: Mercer
authors.affiliation: Research Department of Infection and Population Health, Centre for Sexual Health and HIV Research, University College London, London, UK.
authors.forename: K G
authors.initials: KG
authors.lastname: Jones
authors.affiliation: Research Department of Infection and Population Health, Centre for Sexual Health and HIV Research, University College London, London, UK.
authors.forename: A M
authors.initials: AM
authors.lastname: Johnson
authors.affiliation: Department of Social and Environmental Health Research, Centre for Sexual and Reproductive Health Research, London School of Hygiene and Tropical Medicine, London, UK.|Department of Sociology, University of the Pacific, Stockton, USA.
authors.forename: R
authors.initials: R
authors.lastname: Lewis
authors.affiliation: Department of Social and Environmental Health Research, Centre for Sexual and Reproductive Health Research, London School of Hygiene and Tropical Medicine, London, UK.|MRC/CSO Social and Public Health Sciences Unit, Institute of Wellbeing, University of Glasgow, Glasgow, UK.
authors.forename: K R
authors.initials: KR
authors.lastname: Mitchell
authors.affiliation: Department of Microbiology and Infection Control, University Hospital of North Norway, Tromsø, Norway.
authors.forename: K
authors.identifier: 0000-0002-8194-3208
authors.initials: K
authors.lastname: Gravningen
authors.affiliation: Research Department of Infection and Population Health, Centre for Sexual Health and HIV Research, University College London, London, UK.
authors.forename: S
authors.initials: S
authors.lastname: Clifton
authors.affiliation: Research Department of Infection and Population Health, Centre for Sexual Health and HIV Research, University College London, London, UK.
authors.forename: C
authors.initials: C
authors.lastname: Tanton
authors.affiliation: Research Department of Infection and Population Health, Centre for Sexual Health and HIV Research, University College London, London, UK.
authors.forename: P
authors.initials: P
authors.lastname: Sonnenberg
authors.affiliation: Department of Social and Environmental Health Research, Centre for Sexual and Reproductive Health Research, London School of Hygiene and Tropical Medicine, London, UK.
authors.forename: K
authors.initials: K
authors.lastname: Wellings
authors.affiliation: Division of Primary Care and Public Health, Brighton and Sussex Medical School, University of Brighton, Brighton, UK.
authors.forename: J A
authors.initials: JA
authors.lastname: Cassell
authors.affiliation: Blizard Institute, Barts and the London School of Medicine and Dentistry, London, UK.|Barts Sexual Health Centre, St Bartholomew's Hospital, London, UK.
authors.forename: C S
authors.initials: CS
authors.lastname: Estcourt
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D003625:Data Collection; D005260:Female; D006306:Health Surveys / Q000379:methods*; D006801:Humans; D007407:Interviews as Topic; D008019:Life Style; D008297:Male; D008875:Middle Aged; D011159:Population Surveillance; D012725:Sexual Behavior / Q000523:psychology / Q000706:statistics & numerical data*; D012747:Sexual Partners / Q000145:classification* / Q000523:psychology; D012749:Sexually Transmitted Diseases / Q000453:epidemiology*; D006113:United Kingdom / Q000453:epidemiology; D055815:Young Adult
keywords: CONTACT TRACING; EPIDEMIOLOGY (GENERAL); HEALTH SERV RESEARCH; PARTNER NOTIFICATION; SEXUAL BEHAVIOUR