USE OF DRUGS DOES NOT AFFECT FIT RESULTS

Anticoagulants and nonsteroidal anti-inflammatory drugs (NSAIDs), including aspirin, do not affect the accuracy of fecal immunochemical testing (FIT) used in colorectal cancer (CRC) screening, according to a systematic review and meta-analysis.

"Anticoagulants or NSAIDs do not influence the positive predictive value of FIT results within CRC screening and should therefore not be ceased prior to FIT screening," Dr. Manon C. W. Spaander from Erasmus MC University Medical Center, in Rotterdam, the Netherlands, told Reuters Health by email.

Some studies have suggested that the use of these drugs contributes to false-positive results of fecal blood tests, but previous meta-analyses and systematic reviews (most of which studied guaiac-based fecal occult blood tests) yielded inconclusive results.

Dr. Spaander and colleagues evaluated the positive predictive value for advanced neoplasia (PPV-AN) and the positive predictive value for CRC (PPV-CRC) among oral anticoagulant (OAC) and NSAID users, compared with nonusers, in an average-risk FIT-based CRC screening population. Their meta-analysis included eight studies.

The PPV-AN did not differ significantly between OAC users (37.6%) and users (40.3%), nor did the PPV-CRC (5.7% vs. 6.2%, respectively), the team reports in Gut, online June 5.

There was no significant difference between aspirin/NSAID users and nonusers in PPV-AN (38.2% vs. 39.4%, respectively) or PPV-CRC (6.9% vs. 5.3%) either.

There were no data on sensitivity and specificity of FIT in OAC users, and two studies assessing sensitivity and specificity in aspirin/NSAID users yielded inconsistent results.

"These drugs are often prescribed to patients having serious cardiovascular diseases for which even a temporary cessation could bring certain risks," Dr. Spaander said. "Knowing that these drugs do not influence FIT screening helps in making a well-balanced decision. Guideline recommendations should therefore advise to continue the use of anticoagulants or NSAIDs during FIT screening."

"It is important to note that the influence of the duration and dosage of use is not thoroughly studied," he added. "There may be evidence that the longer the use, the more negative influence this could have on the positive predictive value of FIT. For this reason, we are currently performing a follow-up study on influences of duration, dosage, and type of drugs."

Dr. Ramesh Arasaradnam of University Hospitals Coventry and Warwickshire, in Coventry, U.K., who recently reviewed the diagnostic accuracy of fecal biomarkers in detecting CRC and adenoma in symptomatic patients, told Reuters Health by email, "These findings are helpful, as they give some degree of confidence that we probably do not need to ask participants of bowel-cancer screening programs to stop their medications (anticoagulants and anti-inflammatory drugs) prior to submitting a FIT stool test."

"It's important to note that these findings are based on those having a FIT test for bowel-cancer screening, and one cannot assume that the findings here are directly applicable to those that have symptoms and where FIT test is used to exclude bowel cancer," said Dr. Arasaradnam, who was not involved in the study.