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Contrast-associated acute kidney injury (CA-AKI) is a controversial subject. The available evidence is reassuring that significant acute kidney injury, death, and need for renal replacement therapy are rare after IV contrast administration.

Why does this matter?

Several studies have shown an association between contrast administration and acute kidney injury. Listen to the deep dive Rob Orman and Clay Smith did on contrast nephropathy on ERcast. That podcast was based on these two posts: Contrast Nephropathy Is Real and Contrast Nephropathy Is a Myth. Does intravenous contrast truly cause acute kidney injury? If so, what patients are at risk and what can we do to prevent this from happening?

The Kidney and IV Contrast Relationship: “It’s Complicated”
Key Points:

• CA-AKI may be an indicator of an increased risk of adverse renal outcomes rather than a mediator of such outcomes.

• Confounding and indication bias are major limitations of many CA-AKI studies.

• Changes in creatinine are sensitive for AKI but have low specificity. This may also be due to hemodynamic instability, fluid shifts, and medication effects.

• Significant AKI, death, and the need for renal replacement therapy are very rare after IV contrast administration.

• There are no adequately powered clinical trials showing that prevention of CA-AKI results in a survival benefit.

• History of chronic kidney disease, high-osmolality contrast agents, large contrast volume (>350 ml or 4 ml/kg), or repeat contrast dosing within 72 hours have all been shown to increase the risk of CA-AKI.

• The unintended consequence of excessive concern about CA-AKI is clinicians are more hesitant to order contrasted studies for patients who may benefit from them.

• IV fluid may be beneficial in preventing CA-AKI, but the optimal rate and volume is unknown.

In summary, further investigation is needed to determine if a causal relationship exists between IV contrast and kidney injury, but the available evidence is reassuring that significant AKI, death, and the need for renal replacement therapy are rare after IV contrast administration.

Another Spoonful

• Don’t miss REBEL EM on this topic.

• And Josh Farkas wrote a post in May that is amazing.

• And don’t forget about Rob O and Clay on ERcast – a look at both sides and practical pearls.

Source
Contrast-Associated Acute Kidney Injury. N Engl J Med. 2019 May 30;380(22):2146-2155. doi: 10.1056/NEJMra1805256.

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Current or past substance abuse, mental health diagnosis, age <40 years, and male sex increased risk of subsequent opiate misuse after an initial opiate prescription.

Why does this matter?
Opiate abuse is rampant. Wouldn’t it be nice if we could predict which patients would subsequently abuse opiates after an initial prescription? Maybe this study can help.

New risk factor for opiate abuse – maleness
This was a meta-analysis of 65 studies. They found the risk of subsequent opiate misuse was greatest in patients with current or previous substance use (OR 3.6), mental health diagnosis (OR 2.5), age <40 years (OR 2.2), and male sex (OR 1.2). More and more we are using opiate alternatives for pain. This list of four risk factors should be considered as even higher priority for use of opiate alternatives.

Source
Risk Factors for Misuse of Prescribed Opioids: A Systematic Review and Meta-Analysis. Ann Emerg Med. 2019 Jun 19. pii: S0196-0644(19)30342-7. doi: 10.1016/j.annemergmed.2019.04.019. [Epub ahead of print]

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#4: Sodium Polystyrene for Hyperkalemia and Serious GI Events

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In this large population-based study, sodium polystyrene sulfonate (SPS) use in elderly outpatients was associated with an almost 2-fold higher risk of serious adverse GI events within 30 days of initial prescription. The absolute risk increase was small, however.

Why does this matter?
SPS (brand name Kayexalate) is commonly prescribed for treatment of hyperkalemia, but prior case reports raise concern for serious GI injuries. This large population-based cohort study found a small but significantly increased risk of intestinal ischemia or thrombosis within 30 days of SPS prescription. When other options for treating hyperkalemia exist, should we really still be using this medication?

A terrible gut reaction
This was a Canadian retrospective population-based cohort study of over 20,000 patients over age 65 who received a first time prescription of SPS. The primary outcome was hospitalization or emergency department visit for adverse GI events, including intestinal ischemia/thrombosis, GI ulceration/perforation, or resection/ostomy within 30 days of initial SPS prescription. Compared to a propensity-matched cohort of similar patients who did not receive this medication, the study found 37 (0.2%) adverse GI events in the SPS group compared to 18 (0.1%) in the non-use group during the 30 day follow-up period, a significant difference with a hazard ratio of 1.94 (95% CI 1.10 – 3.41). Intestinal ischemia/thrombosis was the most common type of GI injury.

For more on hyperkalemia, see this emDocs post.

Source
Risk of Hospitalization for Serious Adverse Gastrointestinal Events Associated With Sodium Polystyrene Sulfonate Use in Patients of Advanced Age. JAMA Intern Med. 2019 Jun 10. doi: 10.1001/jamainternmed.2019.0631. [Epub ahead of print]

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