Background: The efficiency of patient safety interventions is not well studied, especially laboratory monitoring for drug therapy. More than one-third of preventable adverse drug events are associated with inadequate monitoring. Current knowledge of decreasing adverse drug events through expanded monitoring programs is lacking.
Design: The authors focused on a laboratory monitoring program (above usual practice) of renin-angiotensin system (RAS) agents to prevent adverse events of hyperkalemia and acute renal failure. They used a probabilistic decision model to estimate cost savings and cost effectiveness (at $30,000 and $10,000 per quality-adjusted life-year (QALY)). Costs included the monitoring program, and offsets from reduced care in 3 populations (overall, chronic kidney disease [CKD], and diabetes).
Main results: Adverse events were most common in those with CKD. Intervening on all new users or the subset with diabetes was almost never expected to be cost saving (probability <1%). But a monitoring program restricted to patients with CKD was expected to be cost saving (probability = 95%). A strategy that intervened on all patients, or those with diabetes, was never cost effective, (probability <1%). But intervening on patients with CKD was estimated to be cost effective (at either cost-effectiveness threshold) at least 95% of the time in the base case.
Conclusions: The authors' findings illustrate that for laboratory monitoring to be cost effective, the patient population must be at high enough risk of adverse events. Further inquiry into the willingness to pay for patient safety interventions is needed.