Objective: To estimate the incidence of Wernicke-Korsakoff syndrome (WKS) before and after the introduction of thiamine enrichment of bread flour in 1991.
Design: Retrospective survey of hospital records. Patient records with the diagnostic codes for Wernicke's encephalopathy (WE) or Korsakoff's psychosis (KP) were reviewed and details of acceptable cases were entered onto a data form.
Setting: All 17 major public general hospitals in the Sydney area (New South Wales), between 1978 and 1993.
Outcome measures: Numbers of confirmed or probable diagnoses of WE, KP or WKS and associated deaths, patient demographic and social characteristics and alcohol intake.
Results: 1,267 patients with WKS were found, with 1,012 acute cases. Although numbers of acute cases may have started to fall before 1991, numbers for the last two years were the lowest of all the 16 years (P = 0.004). Cases of KP outnumbered those of WE by about 3:1 and men outnumbered women 4:1. The peak age was 60-64 years (17%) and beer was the most commonly cited alcoholic drink (71%). The red-cell transketolase test was seldom used for diagnosis (3% of acute cases).
Conclusions: The lower number of "acute" cases in 1992 and 1993 is consistent with a preventive effect of mandatory enrichment of bread with thiamine, but is not conclusive evidence. Longer follow-up of Sydney hospitals, results of postmortem examinations and follow-up in other areas of Australia are required.