A UK general practice database study of prevalence and mortality of people with neural tube defects.

Objective: To investigate the prevalence of neural tube defects (NTDs) in the UK and to compare the mortality rate with that of the general population.

Methods: A cross-sectional study. The General Practice Research Database (GPRD) contains the prescribing and diagnostic records since 1990 of over 4 million people from throughout the UK. All patients aged 10-69 and registered on the database in the years 1994-1997 were included in the study. Patients with a diagnosis of NTD were identified from the database and prevalence and standardized mortality ratios in each year were calculated.

Results: The size of the GPRD reduced during the study period - there were 2116452 patients aged 10-69 years on the database in 1994, of whom 1751 had a prior record of NTD. In 1997 there were 998368 patients, of whom 842 had an NTD. The age standardized prevalence between 1994 and 1997 for NTDs ranged between 7.8 and 8.4 per 10000 for males and 9.0 and 9.4 per 10000 for females aged 10-69 years. There were 27 deaths in patients with a record of NTD over the four-year study period. The standardized mortality ratio for the years 1994 to 1997 for NTDs ranged between 1.9 and 2.9.

Conclusions: These data give an estimate of the prevalence of NTDs in the general population. They also show that those who have survived to age 10 years still have double the mortality of the general population.