Population rates of HIV, gonorrhoea and syphilis diagnoses by sexual orientation in New Zealand

Peter J W Saxton; Susan M McAllister; Callum E Thirkell; Adrian H Ludlam; Jerram P Bateman; Andrew T Anglemyer; Patricia C Priest; Gerard J B Sonder

doi:10.1136/sextrans-2021-055186

Population rates of HIV, gonorrhoea and syphilis diagnoses by sexual orientation in New Zealand

Sex Transm Infect. 2022 Aug;98(5):376-379. doi: 10.1136/sextrans-2021-055186. Epub 2021 Sep 3.

Authors

Peter J W Saxton¹, Susan M McAllister², Callum E Thirkell³, Adrian H Ludlam⁴, Jerram P Bateman², Andrew T Anglemyer^{2

3}, Patricia C Priest², Gerard J B Sonder^{3

5}

Affiliations

¹ School of Population Health, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand p.saxton@auckland.ac.nz.
² Department of Preventive and Social Medicine, University of Otago Medical School, Dunedin, New Zealand.
³ Institute of Environmental Science and Research Ltd, Porirua, New Zealand.
⁴ School of Population Health, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand.
⁵ Department of Internal Medicine, University of Amsterdam, Amsterdam, The Netherlands.

PMID: 34479989
DOI: 10.1136/sextrans-2021-055186

Abstract

Introduction: Globally, gay and bisexual men (GBM) are over-represented in HIV, syphilis and gonorrhoea cases. However, surveillance systems rarely provide meaningful measures of inequity, such as population-specific rates, due to a lack of sexual orientation denominators. HIV, gonorrhoea and syphilis are legally notifiable diseases in New Zealand (NZ); we calculate rates by sexual orientation for the first time.

Methods: We analysed 2019 national surveillance data on HIV, syphilis and gonorrhoea notifications disaggregated by sexual orientation. Unique health records identified duplicate notifications and reinfections. Missing data were imputed from known cases. We used the NZ Health Survey 2014/2015 to estimate population sizes by sexual orientation, measured in two ways (current sexual identity, sexual contact in the previous 12 months with men, women or both). We calculated notification rates per 100 000 for each sexual orientation subgroup and rate ratios.

Results: In 2019, GBM accounted for 76.3%, 65.7% and 39.4% of HIV, syphilis and gonorrhoea notifications, respectively. Population rates per 100 000 for HIV were 158.3 (gay/bisexual men) and 0.5 (heterosexuals); for syphilis, population rates per 100 000 were 1231.1 (gay/bisexual men), 5.0 (lesbian/bisexual women) and 7.6 (heterosexuals); for gonorrhoea (imputed), population rates per 100 000 were 6843.2 (gay/bisexual men), 225.1 (lesbian/bisexual women) and 120.9 (heterosexuals). The rate ratios for GBM compared with heterosexuals were: 348.3 (HIV); 162.7 (syphilis); and 56.6 (gonorrhoea). Inequities remained in sensitivity analysis (substituting sexual identity with sexual behaviour in the previous 12 months).

Conclusion: GBM in NZ experience profound inequities in HIV, syphilis and gonorrhoea. Rate ratios by sexual orientation provide useful 'at-a-glance' measures of inequity in disease incidence.

Keywords: HIV; gonorrhoea; public health; sexual and gender minorities; syphilis.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Female
Gonorrhea* / diagnosis
Gonorrhea* / epidemiology
HIV Infections* / diagnosis
HIV Infections* / epidemiology
Humans
Male
New Zealand / epidemiology
Sexual Behavior
Sexual and Gender Minorities*
Syphilis* / diagnosis
Syphilis* / epidemiology