2013 VOL. 37 NO. 2 AUSTRALIAN AND NEW ZEALAND JOURNAL OF PUBLIC HEALTH 189 © 2013 The Authors. ANZJPH © 2013 Public Health Association of Australia doi: 10.1111/1753-6405.12041 Accuracy of National Health Index numbers for Pacific people in NZ Teresa Lepa, Pauline Norris School of Pharmacy, University of Otago, New Zealand Simon Horsburgh Preventive and Social Medicine, University of Otago, New Zealand Finau Taungapeau Pacific Trust Otago, New Zealand National Health Index (NHI) numbers are used in New Zealand (NZ) to identify patients and link their medical records. The NHI dataset contains ethnicity and other demographic data on each patient and so NHIs are important for measuring disparities in health status, in treatment utilisation and outcomes between ethnic groups, and monitoring attempts to reduce disparities. However, previous studies have found inaccuracies in ethnicity data in the NHI dataset 1-3 that could introduce significant errors into estimates of healthcare need. 4 In the 2006 Census, Pacific people made up 6.9% of the NZ population. This proportion will increase significantly in the future, and Pacific people experience much higher levels of ill-health than other New Zealanders. 5 There are a range of reasons why the NHI system might not capture accurate data about Pacific people, such as healthcare staff’s lack of understanding of Pacific naming conventions. Our study aimed to investigate the accuracy of ethnicity data in the NHI dataset for Pacific people in Dunedin. Most previous studies of the accuracy of ethnicity data have compared administrative records. In an earlier study, we developed a novel methodology of working with communities to collect personal details, and asking the Ministry of Health to check recorded ethnicities against the ones provided by the community members. 6 In this study, we worked with the Pacific Trust Otago and attended events organised by the Trust. The purpose of the study was explained to people attending the events, and they were asked to participate. We asked them to provide date of birth, gender, full name, any other names they might be recorded as, address, length of residence in NZ and ethnicity. We used both paper and an electronic form for data collection. Participants were also given the option of being contacted if their ethnicity was incorrectly recorded in the NHI database. Participants with incomplete information on the paper-based questionnaire were contacted by telephone to provide the missing information. Data was sent to the Ministry of Health in an attempt to locate NHI numbers for participants and find their ethnicity/ies. We compared these ethnicities with those given by participants. For each group, the data was analysed (using Microsoft Excel) based on linked and matched data with age and length of residence in NZ. The 120 participants were from a range of Pacific ethnicities and had a mean age of 38 (standard deviation of 18). A NHI number was found for 118 of the participants. Only 93 of the 118 (79%) Letters