Prostate-specific antigen (PSA) screening and follow-up investigations in Māori and non-Māori men in New Zealand

BACKGROUND: Māori men in New Zealand have higher mortality from prostate cancer, despite having lower incidence rates. The objective of this study was to examine patterns of screening for prostate cancer in primary care and follow-up investigations after an elevated prostate-specific antigen (PSA) result in Māori and non-Māori men in order to help explain the observed differences in incidence and mortality. METHODS: Men aged 40+ years were identified from 31 general practices across the Midland Cancer Network region. Computerised practice records were cross-referenced with laboratory data to determine the number and value of PSA tests undertaken between January 2007 and December 2010. Screening rates were calculated for the year 2010 by age, ethnicity, and practice. For men with an elevated PSA result information on specialist referrals and biopsy was extracted from practice records. Practice characteristics were assessed with respect to screening rates for Māori and non-Māori men. RESULTS: The final study population included 34,960 men aged 40+ years; 14% were Māori. Māori men were less likely to be screened in 2010 compared with non-Māori men (Mantel Haenszel (M-H) age-adjusted risk ratio (RR), 0.52 [95% CI, 0.48, 0.56]). When screened, Māori men were more than twice as likely to have an elevated PSA result compared with non-Māori men (M-H age-adjusted RR, 2.16 [95% CI, 1.42, 3.31]). There were no significant differences between Māori and non-Māori men in the rate of follow-up investigations and cancer detection. Māori provider practices showed equal screening rates for Māori and non-Māori men, but they were also the practices with the lowest overall screening rates. CONCLUSIONS: Māori men were half as likely to be screened compared to non-Māori men. This probably explains the lower reported incidence of prostate cancer for Māori men. Practice characteristics had a major influence on screening rates. Large variation in screening behaviour among practices and differences in follow-up investigations for men with an elevated PSA result seems to reflect the uncertainty among GPs regarding PSA screening and management.