It has been proposed that 6-thioguanine nucleotide levels correlate with inflammatory bowel disease (IBD) in patients treated with azathioprine or 6-mercaptopurine.
Previous studies, most with small sample sizes, yielded conflicting conclusions.
Dr Mark Osterman and colleagues pooled the available data to provide a more precise estimate of this association.
The investigative team searched Medline and Pub Med from 1966 to 2004 and reviewed the reference lists of selected articles.
Both fixed and random-effects models for the analyses were used.
The team tested whether mean/median 6-thioguanine nucleotide levels differed among patients with active disease vs remission.
The investigators assessed whether 6-thioguanine nucleotide levels above a threshold of 230-260 pmol/8 × 108 red blood cells were associated with remission.
When studies reported multiple 6-thioguanine nucleotide threshold values, the team used the data for the lower value.
The investigators identified 55 articles, 12 of which contained data sufficient for inclusion.
|62% with 6-thioguanine nucleotide levels above the threshold value were in remission|
The mean/median 6-thioguanine nucleotide levels were higher among patients in remission than in those with active IBD.
These results showed significant heterogeneity, however, excluding the 1 outlier study eliminated this heterogeneity.
The team found that 62% of patients with 6-thioguanine nucleotide levels above the threshold value were in remission.
Of those below the threshold value, 36% were in remission, but the results showed significant heterogeneity.
Again, after the team excluded the 1 outlier study, the heterogeneity was eliminated.
Dr Osterman's team concluded, “Although prior studies yielded inconsistent conclusions, this analysis strongly supports that higher 6-thioguanine nucleotide levels are associated with clinical remission.”