Introduction and aims: International data suggest recent reductions in rates of macrovascular outcomes while diabetes prevalence increases. We aimed to determine if this was reflected in New Zealand (NZ).
Methods: All NZ residents using health services have a unique number (NHI) for all healthcare encounters. We scanned national hospital discharge and mortality databases from 2005-2012 to ascertain patients with cardiovascular (CV) events, strokes, renal dialysis and amputations in each calendar year using ICD-10 codes. These were compared with the validated National Virtual Diabetes Register (VDR) of patients with known diabetes as at the preceding 31 December.
Results: The absolute number of CV events in people with diabetes fell from >13,000 in 2006 to <11,000 in 2012. Expressed as a rate per 100 patients, this fell progressively from 9.5% to 5.7% per annum (p.a., -44%, r= -0.97; p<0.001). Stroke events rose by 28% from ≈2600 to ≈3300 annually but, as a rate, fell from 1.90% to 1.73%p.a. (-15%, r= -0.87; p<0.02). Renal dialysis numbers rose 21% while the rate fell 20% (both ns), while amputations rose by 29% but the rate of these fell by 15% (p<0.01 for both). VDR ‘membership’, the number of people with diabetes in NZ, rose from 138,200 at end-2005 to 243,125 at end-2013, an increase of 7.3% compound p.a.
Conclusions: While there has been a long-term secular fall in CV mortality and morbidity in many populations, the magnitude of this recent reduction in CV events in NZ (-44% over 6 years) is remarkable. Whilst we have little direct data, this may reflect increased use of cardioprotective therapy, particularly statins, application of the 2003 National Guidelines and the ‘Get Checked’ programme. The apparent prevalence of diabetes in NZ has however increased by 63% over the same period (2005-2012) and by 76% over 2005-2013 - this will, if continued, soon overwhelm the improvement in preventative performance.