This case study examined the utility of regular expressions to identify clinical data relevant to the epidemiology of treatment of hypertension. We designed a software tool that employed regular expressions to identify and extract instances of documented blood pressure values and anti-hypertensive treatment intensification from the text of physician notes. We determined sensitivity, specificity and precision of identification of blood pressure values and anti-hypertensive treatment intensification using a gold standard of manual abstraction of 600 notes by two independent reviewers. The software processed 370 Mb of text per hour, and identified elevated blood pressure documented in free text physician notes with sensitivity and specificity of 98%, and precision of 93.2%. Anti-hypertensive treatment intensification was identified with sensitivity 83.8%, specificity of 95.0%, and precision of 85.9%. Regular expressions can be an effective method for focused information extraction tasks related to high-priority disease areas such as hypertension.

Abstract-Two genetic variants of the ␤-2 adrenergic receptor, 46GϾA and 79CϾG, affect agonist-mediated receptor downregulation and vascular reactivity. We determined whether these variants were associated with hypertension, per se, blood pressure response to dietary sodium, 2 forms of salt-sensitive hypertension (low renin and nonmodulation), and the activity of the renin-angiotensin-aldosterone system. Included are 280 hypertensive and 65 normotensive white subjects who had the 2 ␤-2 adrenergic receptor genotypes available. Of all subjects, 171 hypertensive and 48 normotensive subjects had complete data for intermediate phenotyping and blood pressure evaluation on high-and low-sodium balance. The ␤-2 adrenergic receptor variants were not associated with hypertension per se. However, among hypertensive subjects, the change (from low to high sodium balance) in mean arterial pressure differed significantly by genotype and by diplotype. Compared with all of the other diplotypes combined, 46AA/79CC was associated with a greater change in blood pressure. Furthermore, this diplotype was associated with low-renin (LR) hypertension (identifying 32% of the LR hypertensives), higher plasma aldosterone, and lower plasma renin and serum potassium levels. In conclusion, the 46AA/79CC diplotype is associated with greater blood pressure response to dietary sodium and higher odds of LR hypertension. We propose that the mechanism for the observed association is inadequate suppression of aldosterone with salt intake, implicating the ␤-2 adrenergic receptor in the regulation of aldosterone secretion. This hypothesis was confirmed in isolated glomerulosa cells, where ␤-2 adrenergic receptor stimulation increased aldosterone secretion, whereas blockade reduced the stimulated aldosterone response. Key Words: ␤-2 adrenergic receptor Ⅲ hypertension Ⅲ salt-sensitive hypertension Ⅲ low-renin hypertension Ⅲ single nucleotide polymorphisms Ⅲ haplotypes Ⅲ diplotypes T he ␤ 2 -adrenergic receptor (␤ 2 AR) is generally thought to influence blood pressure homeostasis through sympathetic nervous system-mediated effects on vascular tone and cardiac contractility. 1 The ␤ 2 AR gene is located on the distal segment of the long arm of chromosome 5 (5q33.3 to 34); this region has been identified as a susceptibility locus for blood pressure and hypertension in several genome-wide scans. [2][3][4][5] Two common, nonsynonymous, coding single nucleotide polymorphisms (SNPs) from this gene, 46GϾA (Gly16Arg) and 79CϾG (Gln27Glu), have been shown to affect agonistmediated receptor desensitization and downregulation, 6 -8 as well as vascular reactivity. 9 -11 Because of these findings, these and other polymorphisms in the ␤ 2 AR gene have been extensively investigated in linkage and association studies with human hypertension, with conflicting results. 10 -24 As has been observed with other complex diseases, conflicting findings have been the norm in genetic studies of hypertension, particularly when a distant phenotype (eg, hypertension) has been used. 25...