Cascade effects of laboratory testing are found to be rare in XXXX probability situations: prospective cohort study.

@entity1 @entity258
OBJECTIVES: (1) To investigate the frequency of cascades of further diagnostic investigations and referrals after abnormal laboratory results in situations of @entity258 probability; (2) to investigate pretest and posttest determinants; and (3) to describe the cascades that occur. STUDY DESIGN AND SETTING: Prospective cohort study in primary care in The Netherlands. Numbers of investigations/referrals were recorded during 6 months of follow-up for 256 @entity1 with normal and abnormal laboratory results. The influences of the reason for ordering tests, interpretation of results, and pretest/posttest disease probability were examined. RESULTS: After receiving the laboratory results, the physicians ordered further investigations for 22 (17.3%) @entity1 with abnormal results and for two (1.6%) @entity1 with normal results (P<0.001). They referred 12 (9.4%) @entity1 with abnormal results and eight (6.2%) @entity1 with normal results (P=0.33). Six @entity1 had two investigations and/or referrals, and one @entity1 had three referrals. There were significantly more investigations/referrals for results interpreted as abnormal (P=0.004) and for cases with a high posttest disease probability (P=0.001). CONCLUSION: This study suggests that cascade processes after laboratory testing in situations of @entity258 probability are limited in magnitude and frequency. Improving interpretations may help improve the appropriateness of further investigations and referrals.
