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In this blog post, Dr Corneliu Bolbocean, Senior Researcher in Health Economics, highlights findings from two recent papers examining adulthood quality of life outcomes for those born very pre-term or low birthweight, as well as work showing the better measure of physical or cognitive aspects of health to use.

Premature baby in a medical box


Our researchers have found that being born very preterm/very low birth weight (VP/VLBW) negatively impacts health-related quality of life outcomes in adulthood; furthermore the Health Utility Index Mark 3 (HUI3) is better suited for measuring preterm-related changes to health outcomes compared to Short-form 6D (SF-6D). Dr. Bolbocean and Dr. Petrou have shown that while both measures may be useful when evaluating health outcomes related to birth weight and gestational age, the HUI3 may be more effective for measuring physical or cognitive health.

Very preterm (birth before 32 weeks gestation) and low birth weight (below 1500 g) are associated with increased mortality, neurodevelopmental problems, and socioeconomic disadvantage. These are major concern as they impose significant costs on societies and healthcare systems worldwide. The costs associated with VP/VLBW are not limited to healthcare expenses, because these include lost productivity for affected individuals and their families. There is limited and conflicting evidence about the impact of preterm birth on health-related quality of life (HRQoL) outcomes in adulthood. Some studies suggest a negative impact, while others find no relationship. This is due to methodological challenges in cohort studies, such as sample attrition, which often results in the loss of participants from disadvantaged families or those with impaired outcomes.

Dr. Bolbocean and Dr. Petrou had conducted two studies which have recently been published in leading health economics journals (PharmacoEconomics and Quality of Life Research) to tackle these gaps in the literature. The first study estimated the relationship between very preterm/very low birth weight (VP/VLBW) status and health-related quality of life (HRQoL) outcomes in early adulthood using data from five prospective cohort studies, and identified the specific aspects of HRQoL associated with VP/VLBW status. The subsequent study determined the agreement between two health-related quality of life measures (HUI3 and SF-6D) among adults born very preterm/very low birth weight (VP/VLBW) and controls and identified the reasons for disagreement. It also provided information for the selection of preference-based HRQoL instruments for future research studies that assess the long-term consequences of VP/VLBW or normal birthweight.

The study utilized data from five selected prospective cohort studies within the RECAP Consortium ( Bavarian Longitudinal, Victorian Infant Collaborative, EPICure, New Zealand VLBW, and Norwegian University of Science & Technology Low Birth Weight. The analysis covered the period from data collection to the first assessment in adulthood, with an added examination of repeated HRQoL assessments at 23 and 28 years for two of the cohorts.

The first study, Quality-of-Life Outcomes of Very Preterm or Very Low Birth Weight Adults: Evidence From an Individual Participant Data Meta-Analysis, found that being born VP/VLBW is associated with clinically significant decrements in the HUI3 multi-attribute utility score (HUI3 MAU score) in adulthood. This means that VP/VLBW status has a negative effect on the preference-based health-related quality of life (HRQoL) outcomes. The HUI3 MAU score showed a greater impact of VP/VLBW status than the SF-6D multi-attribute utility score (SF-6D MAU score). This is because the HUI3 MAU score gives more weight to motor function, sensory function, and cognition, which are known to be impacted in VP/VLBW individuals. The results showed that VP/VLBW status is associated with poorer physical and cognitive functioning, but not with socio-emotional or mental health. The study also found that higher levels of maternal education are associated with higher utility scores. Additionally, female sex was found to be associated with a small loss of utility.

The second study, Comparative evaluation of the health utilities index mark 3 and the short form 6D: evidence from an individual participant data meta-analysis of very preterm and very low birthweight adults,  showed significant disagreement between the two measures, with the HUI3 and SF-6D providing unique information on different aspects of health status. Specifically, it found weaker agreement between the HUI3 and SF-6D measures in normal birth weight controls compared to preterm individuals. The results imply that the HUI3 and SF-6D are not interchangeable for cost-utility based decision-making and suggest that the HUI3 may be a better primary instrument for studies quantifying physical and cognitive health, as it specifically asks about vision, dexterity, ambulation, and cognition. This study advances the literature by providing evidence that the differences in descriptive systems explain at least part of the disagreement between the HUI3 and SF-6D measures and is the first to use a meta-analysis in this context. Thus, while both instruments may be useful when evaluating health outcomes related to birth weight and gestational age, the HUI3 may be more effective for measuring physical or cognitive health.

The two studies offer novel insights on the effect of VP/VLBW status on preference-based health-related quality of life outcomes as well as generated new research hypotheses that are being explored. Specifically, our team is currently exploring the impact of socio-demographic factors on HRQoL in VP/VLBW using machine learning techniques and decomposition analysis.

Opinions expressed are those of the author/s and not of the University of Oxford. Readers' comments will be moderated - see our guidelines for further information.


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