# DoH must abandon square root of all evil

It is a simple mathematical symbol, a seemingly abstract concept among the many we use when dealing with numbers. But it now appears to have the power to damage the health of entire practice populations.

Yes, it is the latest instalment in the saga of the square root — or perhaps as it would be referred to in the portentous tones of a 1930s cinema serial, ‘The Square Root of Doom’.

Since its application to prevalence for weighting quality scores, the square root has been implicated in a catalogue of negative developments.

Over the past couple of years we have learned that small practices with high disease prevalence are disadvantaged against their larger neighbours — earning less for treating the same number of patients with a specific condition. And that is before you consider the general effect of the prevalence of Welsh practices, where GPs have to see up to 20 per cent more patients to earn the same as a similar English practice.

In recent weeks, the square root emerged once again as a villain when GP revealed that the formula to adjust prevalence could mean high-prevalence practices being treated as if they had fewer than the average number of patients on a register — penalising some practices by thousands of pounds.

Now the square root is back, hitting the headlines in yet another quality scandal.

Thanks to this mathematical nemesis it seems that deprived practices are discriminated against, earning less per patient, with the result that care is being compromised. The research from Dundee and Glasgow universities suggests that, rather than the quality framework ensuring equally high levels of care across the UK, in fact the prevalence formula cuts funding to practices where the need is greater. This appears to be an extreme consequence of the skewing effect of the formula on smaller practices.

But the researchers have noticed a secondary effect. Practices hit by this prevalence effect are likely to have higher levels of exception reporting. Because these practices have lower incomes per patient for the quality domains, they may not be able to afford to pursue non-compliant patients and decide to exception report them instead.

As a result, all thanks to a square sign, patients in greatest need may be losing out on the very care the quality framework was designed to ensure all patients enjoyed, regardless of location or type of practice.

Even the most hidebound DoH official must now see that the attempt to ‘dampen’ prevalence in this way has been proven to be deeply flawed. If for no other reason, they must eliminate the square root now for the good of patients.

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