Why it’s difficult to get solid data

The target for DHBs to screen 90 per cent of people diagnosed with diabetes accounts for those ineligible, such as people in private care or who are blind. Screening is every two years, but can be at three-year intervals for those at low risk, and annually for people needing close monitoring.

Not all DHBs could say how they were measuring against this target, and the ministry doesn’t track such performance. But the figures that were provided indicate at least 66,000 eligible people aren’t being screened, and that number could be higher.

Capital & Coast DHB had the highest coverage, with approximately 71 per cent screened in the past two years, compared to 49 per cent in Auckland DHB.

Coverage is higher when taken over a three-year period — 59 per cent at Auckland, for example.

New Zealand is among a minority of countries without decent data on eye health, noted a report in February in prestigious medical journal The Lancet. “We just don’t have the data we need to plan equitable eye services,” says Auckland University associate professor Jacqui Ramke, one of 73 experts from 25 countries who contributed to the report.

There’s no central register of people with diabetes — instead, an algorithm estimates prevalence, using health service data to identify people suspected of having the disease.

“We do not have a precise and accurate number of diabetic patients,” Whanganui DHB told the Weekend Herald, in declining to estimate screening coverage. “Current primary care data is incomplete.”