CIN Prophylaxis: witchcraft or EBM?

Kelly AM, Dwamena B, Cronin P, Bernstein SJ & Carlos RC. Meta-analysis: effectiveness of drugs for preventing contrast-induced nephropathy. Annals of internal medicine 2008; 148: 284-294.

RHH Journal Club. July 26th, 2012. Dr Rachel Wadsworth

Full-text article (if available)

Review of prophylaxis for contrast induced nephropathy – increase in serum creatinine greater than 25% or 44.2 micromol/L within 3 days of IV contrast administered in the absence of an alternative cause.

Background

Contrast induced nephropathy – increase in serum creatinine greater than 25% or 44.2 micromol/L within 3 days of IV contrast administered in the absence of an alternative cause.

Common cause of acute renal failure – 0-10% of patients with normal renal function, up to 25% in patients with preexisting renal dysfunction, diabetes, CCF, advancing age, and concurrent administration of nephrotoxic drugs.

Study Design

Meta-analysis of RCTs

Different agents studied

Creatinine measured at baseline and 48 hours in most studies

Methodology

Computerised searches and reviewer selection of relevant studies for inclusion – initially by abstract, then by paper review.

Further data collected from authors where required

Study data

Up to November 2006, 41 studies

Drugs included – dopamine (2), fenoldapam (2), furosemide (2), N-acetylcysteine (26), theophylline (6), simvastatin (1), bicarbonate (1), mannitol (1), ascorbic acid (1), iloprost (1)

Outcomes

Incidence of contrast induced nephropathy as per creatinine measurements

Not looking at associated morbidity, mortality, and hospital stay

Validity

Varying studies – concealment of allocation, similarity of both groups at baseline regarding prognostic indicators, eligibility criteria, blinding of patient, blinding of care provider, blinding of outcome assessor, point estimates and measures of variability for the primary outcome measure, and inclusion of intention-to-treat analysis.

Assessment of heterogeneity – Forest plots, I2 for heterogeneity

Results

Total patient population over 41 trials involved 6379 patients who had elective radiographic procedures involving contrast agents

Studies published between 1994 and 2006 – 15 US trials, 26 performed elsewhere

One trial involved patients having CT, the remainder were following cardiac catheterisation

All but one trial reported creatinine levels at 48 hours, the remaining one at 72 hours

N-acetylcysteine results showed a significantly decreased risk for contrast-induced nephropathy compared with saline alone RR 0.62 (95% CI 0.44 – 0.88)

Theophylline appeared renoprotective – not significant RR 0.49 (95% CI 0.23 – 1.06)

Ascorbic acid – single study – significantly reduced CIN RR 0.23 (95% CI 0.23 – 0.9)

Bicarbonate – single study – significantly reduced CIN RR 0.12 (95% CI 0.02 – 0.95)

Furosemide increased the risk of CIN – RR 3.27 (95% CI 1.48 – 7.26)

Conclusions

Only N-acetylcysteine has enough evidence to support its routine use in clinical practice in view of its limited side effects and safety profile – reduces incidence of contrast induced nephropathy but significance not clearly documented in other outcome measures.

 

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