Saeed Hayati

• Alcalde-Herraiz, Marta; Du, Mike; Sanchez-Parada, Aina; Duarte-Salles, Talita; Palomar-Cros, Anna & Giuliodori, Agustina [Show all 13 contributors for this article] (2026). The effectiveness of HPV vaccination against invasive cervical cancer and related precancerous lesions: a multinational target trial emulation study. The Lancet Primary Care. 2(3). doi: 10.1016/j.lanprc.2026.100114. Full text in Research Archive Show summary

  Background Human Papillomavirus (HPV) vaccines prevent HPV infection and related disease. 15 years after the first HPV vaccination programmes were launched in Europe, their long-term effectiveness can now start to be assessed. We designed a target trial emulation study to estimate the effectiveness of HPV vaccination in preventing invasive cervical cancer and high-grade precancerous lesions using three primary care databases. Methods In this target trial emulation study, we analysed primary care records from the UK (Clinical Practice Research Datalink; data from Sept 9, 1987 to Dec 15, 2023), primary care records linked to hospital records from Catalonia, Spain (Sistema d’Informació per al Desenvolupament de la Investigació en Atenció Primària; Jan 1, 2006 to June 30, 2023), and nationwide linked health registry (including primary care, secondary care, and other health data) in Norway (Norwegian Linked Health Registry; Jan 1, 2018 to Dec 31, 2023), all standardised to the Observational Medical Outcomes Partnership common data model. We included women aged 15 years or younger in 2008, coinciding with the start of public vaccination programmes. Exposure was defined as receiving one or more HPV vaccine doses by age 15 years. The main outcomes included high-grade cervical intraepithelial neoplasia (CIN2+), invasive cervical cancer, and conisation (as a proxy for CIN2+ diagnosis). Vaccinated and unvaccinated cohorts were sequentially matched on an annual basis by year of birth, location, and propensity scores, with up to five vaccinated people matched to an unvaccinated individual. Vaccine effectiveness, based on incidence rate ratios after 15 years of follow-up, were calculated using Poisson regression. Results across databases were meta-analysed using fixed-effects. The specified primary analysis in the original protocol was designed to assess exposure by HPV brand versus unvaccinated populations; however, due to the low number of events by brand, the study was underpowered and the primary analysis was amended to assess HPV vaccination exposure overall (any brand) versus unvaccinated. Findings After two-step matching, our analysis included 81 863 vaccinated and 46 357 unvaccinated women from the UK; 148 214 vaccinated and 39 952 unvaccinated from Spain; and 14 885 vaccinated and 4073 unvaccinated from Norway. Fewer than five cervical cancers were observed per cohort, precluding vaccine effectiveness estimation for this outcome. Meta-analytic vaccine effectiveness at 15 years was 42% (95% CI 6–64) against CIN2+ and 58% (6–82) against conisation. Interpretation Our estimates of vaccine effectiveness against CIN2+ and conisation in Europe align with estimates from previous systematic reviews of randomised controlled trials. We also observed an increased health-seeking behaviour among vaccinated individuals, suggesting that our study might have underestimated vaccine effectiveness. Further studies with longer follow-up are needed to estimate vaccine effectiveness against cervical cancer.

• Zugic, Milica; Pejic, Natasa; Hayati, Saeed; Gelder, Marleen van & Nordeng, Hedvig Marie Egeland (2026). Development of a novel adherence scale for antidepressants in pregnancy: Results from a cross-sectional study. Exploratory Research in Clinical and Social Pharmacy (ERCSP). 21. doi: 10.1016/j.rcsop.2026.100704. Full text in Research Archive
• Mølgaard-Nielsen, Ditte; Mitter, Vera; Lupattelli, Angela; Hoxhaj, Vjola; Navarro, Constanza L. Andaur & Hayati, Saeed [Show all 23 contributors for this article] (2025). Identification of gestational diabetes mellitus in European electronic healthcare databases: insights from the ConcePTION project. BMJ Open. 15(10). doi: 10.1136/bmjopen-2025-102343. Full text in Research Archive
• Asgari, Fatemeh; Alamatsaz, Mohammad H.; Hayati, Saeed & Vitelli, Valeria (2025). Likelihood analysis of latent functional response regression models for sequences of correlated binary data. Scandinavian Journal of Statistics. ISSN 0303-6898. doi: 10.1111/sjos.12773. Full text in Research Archive
• Trinh, Nhung; Houghtaling, Jared; Bernal, Fabian Leonardo Martinez; Hayati, Saeed; Maglanoc, Luigi & Lupattelli, Angela [Show all 8 contributors for this article] (2024). Harmonizing Norwegian registries onto OMOP common data model: Mapping challenges and opportunities for pregnancy and COVID-19 research. International Journal of Medical Informatics. ISSN 1386-5056. 191. doi: 10.1016/j.ijmedinf.2024.105602. Full text in Research Archive Show summary

  Objective Norwegian health registries covering entire population are used for administration, research, and emergency preparedness. We harmonized these data onto the Observational Medical Outcomes Partnership common data model (OMOP CDM) and enrich real-world data in OMOP format with COVID-19 related data. Methods Data from six registries (2018–2021) covering birth registrations, selected primary and secondary care events, vaccinations, and communicable disease notifications were mapped onto the OMOP CDM v5.3. An Extract-Transform-Load (ETL) pipeline was developed on simulated data using data characterization documents and scanning tools. We ran dashboard quality checks, cohort generations, investigated differences between source and mapped data, and refined the ETL accordingly. Results We mapped 1.5 billion rows of data of 5,673,845 individuals. Among these, there were 804,277 pregnancies, 483,585 mothers together with 792,477 children, and 472,948 fathers. We identified 382,516 positive tests for COVID-19 in 380,794 patients. These figures are consistent with results from source data. In addition to 11 million source codes mapped automatically, we mapped 237 non-standard codes to standard concepts and introduced 38 custom concepts to accommodate pregnancy-related terminologies that were not supported by OMOP CDM vocabularies. A total of 3,700/3,705 (99.8%) checks passed. The 5 failed checks could be explained by the nature of the data and only represent a small number of records. Discussion and conclusion Norwegian registry data were successfully harmonized onto OMOP CDM with high level of concordance and provides valuable source for federated COVID-19 related research. Our mapping experience is highly valuable for data partners with Nordic health registries.

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• Trinh, Nhung; Jödicke, Annika M; Català, Martí; Mercadé-Besora, Núria; Hayati, Saeed & Lupattelli, Angela [Show all 8 contributors for this article] (2024). Effectiveness of COVID-19 vaccines to prevent long COVID: data from Norway. The Lancet Respiratory Medicine. ISSN 2213-2600. 12(5), p. e33–e34. doi: 10.1016/S2213-2600(24)00082-1. Full text in Research Archive

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