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

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

Objective: - To evaluate delta check practices and outcomes.

Design: - 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.

Results: - 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%).

Conclusions: - 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.