Chiefs’ Inquiry Corner – 12/23/19

December 23, 2019

Being an outstanding physician and lifelong learner requires stoking the flames of clinical curiosity.  In Chiefs’ Inquiry Corner (CIC) we attempt to succinctly answer actual clinical questions that have been raised on the wards and in the clinics of NYU’s teaching hospitals.  Our answers are not meant to be all encompassing or practice changing but rather to serve as springboards for further exploration. For those of us with short attention spans, we hope CIC satisfies that craving for a morsel of knowledge in a digestible format.

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Nonsteroidal anti-inflammatory (NSAIDs) drugs have a low, but real risk of acute kidney injury, exacerbating hypertension and contributing to electrolyte disturbances. However, the impact of NSAID use on progression of chronic kidney disease (CKD) had previously been unclear. A systematic review and meta-analysis of patients with moderate to severe CKD did not find an association between NSAID use and progression of CKD. However, a subgroup analysis of patients with “high dose NSAID use” (defined as the top quintile or decile of patients included in the respective study) did have a significant association with progression of CKD. As such, NSAIDs are now thought to have a cumulative dose effect on the risk of CKD progression, and an argument can be made for the cautious use of NSAIDs in patients with CKD, particularly for short courses and/or at low doses.
Statins are listed as pregnancy category X due to animal studies that showed convincing associations with fetal anomalies (despite available human data not corroborating this). In this context, guidelines out of the UK recommend that women with familial hypercholesterolemia discontinue statins three months prior to attempting conception and remain off of them until after breastfeeding is complete. Generally, in these patients, screening for coronary artery disease should be undertaken prior to attempting to conceive, in order to determine if there is any contraindication to pregnancy. A large Norwegian registry study showed that pregnancy outcomes are equivalent in women with and without FH.

In a patient with a prolonged QT interval, the risk of developing Torsades de Pointes depends on heart rate. Multiple studies have shown that the widely-used Bazett formula over-corrects at high heart rates and under-corrects at low heart rates. A study of over 6000 patients with prolonged QT confirmed that Bazett had poor sensitivity and specificity for 30-day and 1-year mortality. Performance of the Framingham, Fridericia or Rautaharju varied by age and sex, however, all were superior to the Bazett.  

References: QTc Formulas