If you are admitted to a hospital on the weekend, you have a higher chance of dying than if you are admitted during the week. This is known as the “weekend effect”.

Evidence from the United Kingdom suggests an 11-16% increased risk of death for patients admitted on weekends, mostly driven by emergency admissions. This effect has also been found in the United States and Australia, among Queenslanders admitted for heart attacks.

But while seven-day rosters for doctors and nurses have been touted as a solution to this problem in the UK, the evidence suggests it’s a little more complicated.

What causes the weekend effect?

Generally, there are fewer routine elective procedures and outpatient appointments scheduled on weekends. This means there are fewer nurses and doctors available for emergency care.

During the week, for example, heart surgeons working on elective procedures in hospitals can easily be called away to treat patients admitted through the emergency department. These surgeons may be less readily available at weekends when there are no elective surgeries or outpatient appointments. And there may be longer delays for them to be called in to the hospital for emergency cases.

There is some evidence from the US to support this explanation. Researchers found that a weekend effect for patients presenting with a heart attack (acute myocardial infarction) disappears when they control for the use of invasive treatments such as cardiac catheterization or coronary artery bypass graft (heart bypass).

This suggests that a lower “treatment intensity” for patients presenting at the weekend explains their higher chance of death.

What policies could address this problem?

Policies to address the imbalance of service and workforce availability between weekdays and the weekends should help to alleviate the weekend effect.

The most comprehensive solution would be to introduce seven-day availability of all types of hospital services, scheduling elective procedures and outpatient appointments on weekends as well as weekdays. This would essentially mean having no difference in the type of care offered on different days of the week.

The UK National Health Service (NHS) is taking steps towardsimplementing seven-day services in England, which has generated a heated debate between doctors, NHS managers and politicians on the merits of this proposal.

Costs and benefits of seven-day services

Health bureaucrats looking to address the imbalance between weekend and weekday service availability may try to redistribute the existing workforce supply to be evenly spread throughout the week.

This redistribution of services and workforce should reduce the death rate for weekend admissions. But it would come at the cost of potentially increasing the death rate (and other adverse outcomes) on weekdays where there would be a reduction in services.

Such a redistribution would also involve an increase in financial cost, as higher levels of pay are likely to be necessary to encourage doctors and nurses to work more of their hours at weekends. One of our recent studies suggests that junior doctors in Australia would expect a 25-50% increase in salary to sacrifice control over their working hours and/or be available for more frequent on-call time.

A similar study finds a premium of 10-15% of salary is needed to encourage nurses to work at weekends as well as on weekdays.

An important paper has recently tried to quantify the costs and benefits of introducing seven-day services in the UK. It calculates the potential “lives saved” by eliminating the weekend effect and uses cost estimates produced by hospitals which have been trialling seven-day services.

The authors are able to quantify “cost-effectiveness” by comparing the cost per year of life saved (implied by their analysis) with the National Institute for Clinical Excellence’s “cost-effectiveness threshold” for life-years saved. This is generally thought to be around £20,000 per life year.

The authors find that introducing seven-day services does not come close to cost-effectiveness. The cost of avoiding excess deaths from weekend admissions is too high relative to other effective interventions the NHS could spend its money on.

At the heart of this debate is a trade-off between equity and efficiency. It is more “efficient” to have less service availability at weekends and more on weekdays, because of the increased costs associated with employing doctors and nurses at weekends. But we have to decide if we are willing to accept the resulting inequity: that patients admitted on weekends may have a poorer access to care and a resulting increase in mortality.

Should Australia move to seven-day services?

The debate over seven-day services in the UK is highly politicised, and influenced by the current government’s agenda to make the NHS more patient-focused.

We have a different health-care system and political climate in Australia and are yet to have this debate. With a much larger private sector and public hospitals run by state governments, there is not a single national focus for policy debate about public hospital services.

Nevertheless, the current evidence from abroad suggests that forcing hospitals to provide all services equally distributed through the week is not the answer.

While the weekend effect on mortality may seem large in relative terms (10-16%), it is tempered by the low mortality rate in absolute terms. The 10% relative increase of death in the UK data translates to only 0.4 percentage points (3.7% on weekdays vs 4.1% on weekends for emergency admissions).

Further, the cost-effectiveness study from the UK highlights the potentially high costs of seven day services in relation to any health benefits. Further research is needed, especially on the cost side and in understanding the drivers of the weekend effect in different clinical areas of patient care.

This article originally appeared on The Conversation.