[Different methods used to estimate the prevalence of hypothyroidism, Cadiz, Spain]

Hypothyroidism (HT) is a common condition in clinical practice. There is a paucity of recent data on its prevalence in Spain, suggesting the need for an updated estimate and therefore the aim of this study was to determine its prevalence in the province of Cádiz.

We obtained data relative to medical prescriptions for group H03AA drugs issued in primary care centers attached to the Andalusian Health Service in the province of Cadiz in 2012. Prevalence was estimated on the basis of the defined daily dose (DDD), the prescribed daily dose (DDP) and treated patient records (TPR). We present the estimated prevalence and odds ratio by gender, with a confidence interval of 95%.

Prevalence of HT in 2012 in the population aged 15 years and over in the province of Cadiz was 1.36% (CI95: 1.33%-1.38%) based on DDD; 2.60% (CI95: 2.54%-2.66%) based on DDP; and 3.10% (CI95: 2.85%-2.93%) based on TPR. Median age was 56 years (IQR: 43 to 68). Prevalence (TPR) by gender was 0.75% in men and 5.36% in women [OR 7.26 (CI95: 7.02-7.52)]. The greatest prevalence, 9.35%, was found in the group of women aged 51 to 70 years.

Prevalence of HT in Cadiz is high, mainly affects women. Current prescribing systems allowed us to obtain TPRs, which have been shown to be a more valuable tool than DDDs for estimating HT prevalence.