QALYs in obstetrics: not the whole story.

Abstract

‘Universal ultrasound scanning for macrosomia… is not cost-effective… is not warranted.’ Wastlund et al. offer this conclusion from a cost-effectiveness analysis (CEA) of universal versus selective screening for macrosomia with ultrasound BJOG, 2019;126:1243–5). This decisive statement reveals interesting observations about CEA in obstetrics. The authors conclude that universal screening for macrosomia is not cost-effective based on a widely accepted threshold in the UK: €20,000–30,000 per quality-adjusted life year (QALY). As the incremental cost-effectiveness ratio (ICER) of universal screening with induction of labour for macrosomia was €52,719 per QALY when compared with selective ultrasound plus labour induction, it is not considered to be cost-effective. Intriguingly, this is cost-effective by a US standard of <USD 100,000 per QALY. Also, cost-effectiveness thresholds – such as P-values or blood pressure cutoffs – are fairly arbitrary and are highly contested. The binary summary based on a yes or no conclusion about cost-effectiveness fails to capture this nuance. In the typical CEA, all costs are converted to a standard cost and all outcomes are converted to a single effectiveness outcome – the QALY. Using QALYs is useful so that unrelated outcomes, or outcomes of disparate clinical significance, can be compared across CEAs. This is right-minded. Without a single health outcome measure, it is nearly impossible for a health system to decide whether, for instance, they should invest in an intervention to reduce caesarean sections or one to prevent neonatal morbidity. Although there are well-reasoned arguments for its use in CEA, QALYs in obstetrics are often misinterpreted and sometimes misused. Important questions about CEA in obstetrics are unresolved and may be unresolvable. Are maternal and neonatal QALYs equal? Should maternal and neonatal QALYs be combined? When a pregnancy results in the death of the mother or newborn, can QALYs account fully for this effect on the family or community? The complexity and conflicting nature of the maternal-fetal dyad is often lost due to the pedantic simplicity and opaqueness of the QALY. In the study by Westland et al., universal ultrasound reduced the number of deaths by 23 in 100 000 deliveries, at a cost of about €500,000 per death. Whether that cost is ‘worth it’ may be more consequential than whether to spend €50,000 for an additional QALY. Surprisingly few studies attempt to estimate the health utility state of families dealing an adverse obstetric outcome. Because of this, the experience of the patient may be lost. In converting all obstetric outcomes to QALY for simplicity and standardisation, there is a risk of ascribing too much validity and weight to this outcome measure. Although QALYs are useful, they are clearly not the whole story. The reader of a CEA (or policy maker) should look beyond the dichotomous conclusion of cost-effectiveness by a given threshold. Cost-effectiveness is less ‘true’ or ‘false,’ and more ‘if’ and ‘when’. An understanding of the unique outcome trade-offs is needed. New data describing the short- and long-term health states of families affected by adverse obstetric events are also needed. Perhaps something to replace or supplement QALY is needed. Looking beyond QALY, providers and patients may find that the answer to the question ‘is it worth it?’ differs from the answer given by a cost-effectiveness threshold. None declared. Completed disclosure of interests form available to view online as supporting information. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.