Does Hypertension Develop After Reflux Nephropathy in Childhood? A Critical Review of the Recent English Literature

Urinary tract infection in children is important, not only because of the acute infectious episode, but also because of underlying urologic abnormalities and consequential renal scarring which, in turn, is believed to cause long-term sequelae such as hypertension, renal insufficiency, and complications in pregnancy. It is reasonable to anticipate the development of hypertension after renal scarring, as the renin-angiotensin-aldosterone system is activated; however, evidence for this widely held concept is scanty. In a survey of the English literature from 1989-2003, nine articles reporting the prevalence of hypertension in reflux nephropathy were identified and are described in this review. From six cohort studies that followed patients for 15-29 years to adulthood, the reported risk of hypertension ranged from 5.6-27.9%; however, only one study reported a significantly greater risk in patients with renal scarring compared to a non-scarred control group. In four other studies that also included non-scarred, comparator groups, the risks were similar in patients and controls. There was a trend towards increasing blood pressure with more severe scarring. The observed variation in results was likely due to different methodologic limitations, such as referral bias, a significant percentage of defaulters, failure to correct for confounding factors, and different methods of measuring blood pressure and defining hypertension. These and related issues are critically reviewed here.