CRD summary

The authors concluded that sodium bicarbonate was more effective than normal saline in preventing contrast media-induced nephropathy, but results differed among trials. Further research is required. Evidence appeared to support the authors’ cautious conclusions, but the lack of reporting of review methods and trials quality make it difficult to comment on the reliability of the conclusions.

Authors' objectives

To compare the effectiveness of hydration therapy using sodium bicarbonate with normal saline for the prevention of contrast induced nephropathy.

Searching

MEDLINE and the Cochrane Library were searched with no year or language restrictions. Some search terms were reported. In addition, reference lists and published abstracts from the Proceedings of American College of Cardiology 56th scientific session and the AHA (American Heart Association) Scientific Sessions (2006 and 2007) were screened. Index Medicus was handsearched.

Study selection

Randomised controlled trials (RCTs) that compared periprocedural hydration using sodium bicarbonate with normal saline for the prevention of contrast induced nephropathy were eligible for inclusion.

The included trials evaluated a variety of contrast media including iopamidol, iodixanol, iomeprol, ioxilan and ioxaglate. Patients in the included trials differed with respect to baseline renal function (serum creatinine ranged 1.0 to 2.04 mg/dL) and used different volumes of contrast (range 100 to 290 mL). Most patients were male and the mean age ranged from 64 to 76 years. Where reported, most patients were undergoing cardiac catheterisation. Contrast induced nephropathy was defined as an increase of 25% or more in the serum creatinine. The review also assessed the need for renal replacement therapy and in-hospital mortality.

The authors did not state how papers were selected for the review, or how many reviewers performed the selection.

Assessment of study quality

The authors did not state that they assessed validity.

Data extraction

The numbers of patients developing contrast induced nephropathy were extracted on an intention-to-treat basis and used to calculate odds ratios with 95% confidence intervals.

The authors did not state how data were extracted for the review, or how many reviewers performed the data extraction.

Methods of synthesis

A pooled odds ratio with 95% confidence interval was calculated using a random-effects model. Heterogeneity was assessed using the Cochrane Q test and the I² statistic. Publication bias was assessed using the test of Egger and the trim-and-fill method used to adjust for any publication bias.

Results of the review

Nine randomised controlled trials (RCTs) were included (n=2,043 patients). The authors stated that most trials were not blinded.

Sodium bicarbonate was associated with a statistically significant reduction in contrast induced nephropathy compared to normal saline, odds ratio 0.45 (95% confidence interval (CI0: 0.26 to 0.79). Statistically significant moderate heterogeneity was found (p=0.016, I² 57.3%). There was evidence of publication bias (p=0.012). After adjusting for presumed unpublished trials, there was no significant difference in the incidence of contrast induced nephropathy between sodium bicarbonate and normal saline, odds ratio 0.65 (95% CI: 0.36 to 1.20).

There was no significant difference between sodium bicarbonate and normal saline in rates of need for renal replacement therapy (eight RCTs; p=0.330) or in-hospital mortality (four RCTs; p=0.499).

Authors' conclusions

Sodium bicarbonate was more effective than normal saline in preventing contrast media-induced nephropathy, but results differed among trials. Further research is required.

CRD commentary

The review question was clearly stated and inclusion criteria appropriately defined. Several relevant sources were searched and no language restrictions were applied. Some attempts were made to minimise publication bias but evidence of publication bias was found. Methods used to select studies and extract data were not described, so it is not known whether efforts were made to reduce reviewer errors and bias. Only RCTs were included but trial validity was not assessed, so results from these trials and any synthesis may not be reliable. Data were pooled using meta-analysis and statistical heterogeneity was assessed. The analysis was repeated after adjusting for potential publication bias. Some differences between trial characteristics were discussed as potential causes of the detected heterogeneity. The evidence appeared to support the authors’ cautious conclusions, but the lack of reporting of review methods and study quality make it difficult to comment on the reliability of the conclusions.

Implications of the review for practice and research

Practice: The authors did not state any implications for practice.

Research: The authors stated that further randomised controlled trials are required to compare sodium bicarbonate with normal saline for the prevention of contrast induced nephropathy.

Funding

Not stated.

Bibliographic details

Joannidis M, Schmid M, Wiedermann C J. Prevention of contrast media-induced nephropathy by isotonic sodium bicarbonate: a meta-analysis. Wiener Klinische Wochenschrift 2008; 120(23-24): 742-748. [PubMed: 19122985]

Original Paper URL

http://www.springerlink.com/content/u30x603504402204/?p=d4e87ece2bf44ed181d2bd79c378fe55&pi=1

Indexing Status

Subject indexing assigned by NLM

MeSH

Acute Kidney Injury /chemically induced /mortality /prevention & control; Carbonates /administration & dosage; Contrast Media /adverse effects; Fluid Therapy /methods; Hospital Mortality; Humans; Kidney Function Tests; Odds Ratio; Randomized Controlled Trials as Topic; Renal Dialysis /utilization; Sodium Chloride; Survival Rate; Utilization Review

AccessionNumber

12009102514

Database entry date

16/09/2009

Record Status

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.