Increased incidence of gonorrhoea and chlamydia in Greenland 1990-2012

Background: Since the 1970s, Greenland has presented the highest reported incidence rates of the sexually transmitted infections (STIs) gonorrhoea and chlamydia in the Arctic regions. Objective: This study aims to describe sex-and age-specific incidence rates of gonorrhoea and chlamydia from 1990 to 2012 in Greenland, and to evaluate if changes in case definitions, diagnostic procedures and implementation of STI interventions during the period coincide with rate changes. Design: Gonorrhoea and chlamydia cases were identified from the national STI surveillance. For 1990-2008, STI cases were identified from weekly notified aggregated data. For 2009-2012, cases were identified in person-identifiable national registers. We used log-linear Poisson regression to calculate incidence rates (IRs) and incidence rate ratios (IRRs) with 95% confidence intervals (95% CI). Analyses were stratified according to sex, age and calendar period. Results: Gonorrhoea and chlamydia incidence rates have increased since 1995 to reach 2,555 per 100,000 person-years (PY) for gonorrhoea and 6,403 per 100,000 PY for chlamydia in 2012. From 2006 to 2012, the incidence rates among young adults aged 15-19 years were 8,187 and 22,515 per 100,000 PY for gonorrhoea and chlamydia, respectively. Changes in surveillance reporting did not seem to influence the incidence rates for either disease, whereas a change in diagnostic test coincided with an increased incidence of chlamydia. Conclusion: Overall, the incidence of chlamydia in Greenland increased during the study period, whereas the incidence of gonorrhoea decreased until 1995 but increased thereafter. Young adults aged 15-24 years were at highest risk of infection. The increase in incidence rates was independent of changes in case definitions, whereas an observed increase in chlamydia incidence in 2005 coincided with a change in diagnostic test. None of the STI interventions launched after 1995 seemed to coincide with decreasing national incidence rates.