Delta Check Practices and Outcomes: A Q-Probes Study Involving 49 Health Care Facilities and 6541 Delta Check Alerts

- Delta checks serve as a patient-based quality control tool to detect testing problems.

- To evaluate delta check practices and outcomes.

- Q-Probes participants provided information about delta check policies and procedures. Information about investigations, problems, and corrective actions was prospectively collected for up to 100 testing episodes involving delta check alerts.

- Among 4505 testing episodes involving 6541 delta check alerts, the median frequencies of actions taken among 49 laboratories were clinical review, 38.0%; retest, 25.0%, or recheck, 20.2%; current specimen, nothing, 15.4%; analytical check, 5.0%; other; 2%; and retest or check previous specimen, 0%. Rates of any action taken by analyte ranged from 84 of 179 (46.9%) for glucose to 748 of 868 (86.2%) for hemoglobin and potassium. Among 4505 testing episodes, nontesting problems included physiologic causes (1472; 32.7%); treatment causes (1318; 19.2%); and transfusion causes (846; 9.9%). Testing problems included 77 interference (1.7%), 62 contamination (1.4%), 51 clotting (1.1%), 27 other (0.6%), 12 mislabeling (0.3%), and 5 analytical (0.1%). Testing problems by analyte ranged from 13 of 457 (2.8%) for blood urea nitrogen to 12 of 46 (26.1%) for mean corpuscular hemoglobin concentration. Using more delta check analytes was associated with detecting more testing problems (P = .04). More delta check alerts per testing episode resulted in more actions taken (P = .001) and more problems identified (P < .001). The most common outcome among 4500 testing episodes was reporting results without modifications or comments in 2512 (55.8%); results were not reported in 136 (3.0%).

- Actions taken in response to delta check alerts varied widely, and most testing problems detected were preanalytical. Using a higher number of different analytes and evaluating previous specimens may improve delta check practices.