Ethnic and Geographic Variations in the Incidence of Pancreatitis and Post-pancreatitis Diabetes Mellitus in New Zealand: a Nationwide Population-based Study

Aim: To determine the incidence of acute pancreatitis (AP), chronic pancreatitis (CP), and post-pancreatitis diabetes mellitus (DP) in New Zealand, and the effect of ethnic and geographic variations.

Methods: Data were collected from all district health boards in New Zealand by the Ministry of Health (Manatū Hauora). Diagnosis of AP, CP and DP was determined by the International Classification of Diseases-10 codes. Incidence rates per 100,000 population per year were calculated using incident AP, CP and DP cases as the numerator, and the adult resident population of New Zealand as the denominator. Poisson distribution was used to estimate 95% confidence intervals. The district health board domicile codes and corresponding incidence rates were used to map geographical variations for AP, CP and DP.

Results: On average, 2,072 new cases of AP, CP and DP were diagnosed in New Zealand every year. The crude incidence of AP was 58.42 [57.55, 59.30], CP - 3.97 [3.74, 4.20], and DP - 7.95 [7.62, 8.27] per 100,000 population per year. Māori had the highest incidence of AP (95.21 [91.74, 98.68] per 100,000 population per year), CP (6.27 [5.37, 7.16] per 100,000 population per year), and DP (18.23 [16.71, 19.76] per 100,000 population per year). Incidence of AP and DP was at least 1.8 and 2.6 times higher in Māori than New Zealand Europeans in every age group, and incidence of DP was at least 1.9 times higher in Pacific people than New Zealand Europeans in every age group. Auckland/Northland had the highest incidence of AP (135.25 [134.82, 135.68] per 100,000 population), and CP (9.03 [8.60, 9.46] per 100,000 population), while Lakes/Waikato had the highest incidence of DP (20.64 [20.21, 21.07] per 100,000 population) in New Zealand.

Conclusions: New Zealanders have a very high incidence rate of AP, with Māori having the highest reported incidence of AP worldwide. There is a significant geographic variation in incidence of pancreatic diseases, with the Upper North Island having the highest incidence rates of AP, CP and DP in the country. Future high-quality studies are required to understand the mechanisms of pancreatitis and DP in order to develop preventive and therapeutic strategies that would benefit New Zealanders in general and Māori in particular.