We developed a screening tool to detect several high-risk situations with the potential to lead to a major ADE. Once detected, an alert was sent to clinical pharmacists, not directly to prescribers. Our main finding was that PharmaCheck was effective at detecting high-risk situations, with 447 situations identified during the study period. These alerts were considered relevant in 90 cases, with a suggested intervention addressed to the physician (intervention PPV = 20.1%). The final clinical PPV including the pharmacist’s intervention was 71%—five times higher than if the pharmacist had not ruled out the non-clinically relevant alerts (final clinical PPV without a pharmacist = 14%).
PharmaCheck performance in the detection of high-risk situations
Patient characteristics associated with pharmacists’ interventions
In the present study, decisions to intervene appeared to be moderately positively correlated with patient age (the likelihood of pharmaceutical intervention increased with age). There was clear evidence that older patients were proportionately more polymorbid and polymedicated than younger patients, which exposed them to an increased risk of ADEs and, therefore, to triggering alerts and interventions. In addition, elderly patients’ intrinsic characteristics may help explain this greater likelihood of intervention: pharmacokinetic and pharmacodynamic properties are age-related, and this population is exposed to more adverse events (e.g., reduced renal elimination, greater susceptibility to anticholinergic effects) that readily prompt pharmacists to intervene. (26–28)
Intervention PPV associated with PharmaCheck
The present study assumed that the intervention PPV reflected the specificity of a CDSS integrated into a CPOE and, thus, PharmaCheck’s performance. Ninety of the 447 alerts led to a pharmaceutical intervention (intervention PPV = 20.1%). According to a systematic review that assessed the reported PPV (ratio of relevant drug alerts to the total number of alerts), this indicator varied considerably, from 5.8% to 83%, with the majority of results falling between 20% and 40%. (29) It should be noted that few studies have analyzed the impact of advanced CDSS dedicated to clinical pharmacists for the prevention of selected, specific, high-risk situations. In such settings, intervention PPVs varied from 8% to 51%. (30–33) Although published studies have not systematically described reasons for non-intervention, different elements help to explain disparities in these results: logistical limitations (not enough resources to process every alert); technical limitations (low specificity linked to absent or insufficiently structured data in the EHRs); limitations associated with workflows (repetitive alerts that have already been analyzed, risk situations that physicians have already considered). (30–33) Our study identified three factors that may explain the disparities between the intervention PPVs for the different clinical rules. First, the nature and informative quality of the trigger elements (defined as any set of data in the EHR enabling the appropriate assessment of a clinical situation) affected alert relevance. Second, the clinical context and the physician’s awareness of the risk situation enabled a better assessment of the need for an intervention. Third, additional redundant electronic safeguards (targeting known risk situations already and partially made safe by a CDSS) also influenced pharmaceutical interventions.
Nature and information quality of trigger elements integrated into the CDSS
As already noted, most of the clinical rules (12/20) concerned the ‘drug prescription with abnormal laboratory values’ risk category, accounting for more than half of the alerts (54.1%) and with an intervention PPV of 26.9%. Although, compared to alerts concerning other clinical rules, alerts concerning drug–laboratory interactions seemed to be the most relevant (reported intervention PPV up to 83%). (29) It should be noted that in our study, their relevance depended on the sub-category of risk and its associated triggers. We observed the highest intervention PPV (33.9%) in the ‘drugs prescribed in the presence of renal failure’ category, as these alerts are based on the prescription of a drug (direct oral anticoagulant, metformin, colchicine, and morphine) and an estimated level of renal function. To go one step further with these alerts, PharmaCheck was set to display several renal function values: estimated glomerular filtration rate (eGFR) based on the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation and estimated creatinine clearance using the Cockcroft–Gault (CG) equation, calculated using actual and ideal body weight but selecting the lowest one. (34,35) Thus, most of the alerts were triggered by the CG with ideal body-weight clearance, whereas our EHRs calculated and displayed eGFR based on the CKD-EPI formula. Automatically providing and comparing these renal function estimates added value; otherwise, a time-consuming manual calculation would have been required.
In contrast, the second most frequent alert category was ‘contraindicated medications or medications to be used with caution’ (28.4% of alerts), but it was associated with the lowest intervention PPV (3.1%), which may translate into a low specificity clinical rule (since a low number of alerts was considered relevant to trigger an intervention with the physician). The development of clinical rules involving patient problems is challenging as these trigger elements are not commonly structured in an unequivocal way (e.g., using ICD-10 terminology and/or SNOMED CT). (36) Several studies have shown that the reliability of free-text searches through EHRs to characterize patients’ problems is uncertain, with a sensitivity varying from 1% to 46%. (37) The inaccuracy of free-text searching is underpinned by the lack of specificity in the problems described in the EHR on the one hand (problems mentioned with little or no diagnostic support may increase false-positives) and lack of sensitivity on the other (choosing a set of non-exhaustive trigger words for problem characterization may increase the false-negative rate). (38,39) In the present study, the search for terms characterizing patient problems in their admission notes (chapter on ‘relevant comorbidities’ and ‘active problems’) was not sufficiently specific. The absence of intervention was mainly related to false-positive alerts (e.g., ruling out epilepsy or a history of alcohol withdrawal seizures was sufficient to trigger an alert in the presence of a drug lowering the patient’s seizure threshold). We believe that these issues will be partially solved by the General Internal Medicine Department’s recent deployment of a structured patient-problem list, the use of which has led to a clear decrease in free-text entries over the last three years on several wards. (40)
Clinical context and physicians’ awareness of risk situations
Two clinical rules involving DDIs were the third reason for triggering an alert, with an intervention PPV of 28.2% (71 alerts led to 20 interventions). However, given the clinical context, it should be noted that only the clinical rule regarding the interaction of two anticoagulant drugs led to pharmaceutical interventions (intervention PPV = 52.6%). In contrast, pharmacists never intervened for interactions between two serotoninergic drugs, with an increased risk of serotonin syndrome. It has been shown that integrating contextual information is a key factor in improving the PPV for medication alerts and particularly for DDI alerts. (29) Additionally, two of the most significant contextual factors that should help clinicians’ decision-making within a CDSS are the ‘severity of the effect’ and the ‘patient’s clinical condition’; however, they remain difficult to consult using clinical rules based on explicit criteria (e.g., laboratory values, demographic data). Thus, contextual factors depend mainly on clinicians’ judgment. (41) Clearly, the prescription of two anticoagulants should be avoided, given the ‘severity of effect’ of the pharmacodynamic interaction. Furthermore, all of these alerts were accompanied by an intervention except in situations involving the misuse of the CPOE (two anticoagulants prescribed simultaneously when they should be alternated and for which the temporal sequence was clearly indicated in the free-text section of the medication order aimed at the nurse). On the other hand, no interventions were carried out when two serotoninergic drugs were combined, since, in each case, the doses were low to medium, the patient’s clinical context was incompatible with a serotoninergic syndrome, and the treatments were being taken on a long-term basis and were well tolerated. Similarly, considering the clinical context helps to explain the disparity between PPVs for alerts regarding a drug prescription combined with an abnormal laboratory value, indicating a potential overdosage or the risk of an adverse effect: in all the prescriptions for blood-glucose-lowering drugs associated with hypoglycemia, the situation was already being managed at the time of screening, and the PPV was zero. Physicians closely monitored heparin prescriptions in the presence of thrombopenia, as most of the patients concerned were still being monitored for hemopathy. Moreover, the likelihood of heparin‐induced thrombocytopenia was very limited and the PPV was low. Finally, the intervention PPV was higher in the presence of hypokaliemia on digoxin, or hyperlactatemia on metformin, due to the severity of the adverse effects and an unfavorable benefit–risk ratio. (42,43) PharmaCheck’s development has taken into account the need to contextualize alerts using patient data (e.g., medication and dosage, previous laboratory values). Thus, a significant effort has been made to display useful patient data from their EHRs directly adjacent to alerts, thus increasing the screening tool’s ergonomics. (44)
Redundant safeguards
Alerts associated with an inappropriate mode of administration were the least frequently triggered (n = 7) and had the lowest proportional intervention PPV (14.3%). These clinical rules targeted drugs described in the list of ‘never events’ for which the occurrence of an ADE may lead to a life-threatening situation. (20) Thus, methotrexate and potassium chloride were already the targets of priority safety actions when PharmaCheck was deployed. Among the strategies that can be used to prevent a specific ADE, medication dosing support (providing common medication dosages) has been shown to be effective. (45,46) However, deviations from prescriptions are still theoretically possible; for example, a prescription of two separate single doses of methotrexate at an interval of less than 7 days is possible despite a locked-in administration frequency option (once a week) and a duplicate alert trigger. PharmaCheck was also used to complete the arsenal of tools for preventing ‘never events’, even though their probability of occurrence is very low, as shown by the low intervention PPV (the only intervention concerned a severe hypokalemia, for which a potassium chloride infusion rate of > 10 mmol/hour was prescribed without any documentation on cardiac monitoring). Similarly, a clinical rule concerning the prescription of vitamin K antagonists and supra-therapeutic INR (36 alerts) induced few interventions (intervention PPV = 19.40%) thanks to the prescription security provided by corollary orders (INR are automatically ordered and displayed for each vitamin K antagonists prescription/dose adjustment). (45,47)
Studying PharmaCheck’s performance in detecting high-risk situations led us to define the three characteristics of an ‘ideal’ alert—one that would be triggered for most relevant situations.
- The alert should be based on the selection of a trigger or set of triggers that best characterize a clinical situation (e.g., alerts concerning a drug prescription with renal failure should be based on the most relevant weight value between measured, adjusted, or ideal body-weight should also be triggered according to the evolution of renal function, taking into account previous measurements).
- The alert’s content should facilitate clinical contextualization by highlighting the risk factors likely to trigger an intervention or, on the contrary, protective factors unlikely to trigger an intervention (e.g., displaying the list of prescribed CYP3A4-inhibiting drugs that constitute an additional risk factor for the accumulation of direct oral anticoagulants and an acute renal failure alert; displaying any prescription for potassium supplementation indicating the management of hypokaliemia when the alert for the contraindication of digoxin for hypokaliemia is activated).
- Alerts should be displayed in an order that allows priority treatment for the riskiest situations (e.g., considering the patient’s age or whether an alert is already redundant).
PharmaCheck’s impact on the activity of clinical pharmacists
PharmaCheck’s integration into daily clinical pharmacy routines
A total of 447 alerts were triggered, and PharmaCheck produced between 3 and 4 new alerts per day. Concerning workloads, the time required to process alerts was not accurately measured (estimated at 1 to 3 hours per day, including reviewing new alerts and repetitive alerts occurring during several rounds of PharmaCheck use). Users nevertheless agreed on the need to allocate more time for analysis when alerts are first triggered (compared to an alert that has already been analyzed and requires a simple follow-up). Using PharmaCheck daily seemed to be a reasonable use of time—a means to avoid missing any important warnings resulting from new or changed prescriptions and potentially leading to an ADE. One study has estimated that using a monitoring system involving a pharmacist requires 1.5 hours per day (working with 3.6 alerts/day). In addition, those authors calculated that when alerts could not be analyzed daily, 36% of the notified situations handled retroactively (after 24 hours) were associated with an ADE. (30) This suggests that screening would be most effective as part of daily routines.
PharmaCheck’s addition to traditional on-ward clinical pharmacy activities
Fifteen of the 20 clinical rules led to an intervention, with a final clinical PPV of 71% when alerts were filtered by a clinical pharmacist. This rate is close to those observed when using similar screening tools dedicated to pharmacists (63% to 83% for 300 to 554 interventions). (31–33) PharmaCheck was based on a back-office approach complementing standard clinical pharmacy activities (medication review during medical rounds), and the majority of interventions were carried out by telephone (as only a minority of situations involved patients admitted to a ward covered by a clinical pharmacist). A previous study in our participating General Internal Medicine ward showed a slightly higher final clinical PPV, around 80%. (19) In contrast, several studies have shown that acceptance rates for pharmacists’ interventions were significantly lower for back-office or written interventions than for on-ward or verbal advice or interventions. (19,48) A pharmacist’s presence on a ward is more conducive to interventions as visibility and recognition are better and timing has a greater impact. There is also better contextualization because the information used is captured during pharmacists’ visits. (49) Indeed, combining an on-ward approach with back-office screening and interventions for high-risk situations is an efficient and acceptably safe way to expand a clinical pharmacist’s coverage (and workload): in addition to 2–5 weekly typical on-ward visits covering 15–45 inpatients, PharmaCheck back-office use makes it possible to monitor 20 high-risk situations for approximately 200 additional patients every day.
The main reason (85.2%) why physicians did not follow therapeutic adjustment proposals was a positive benefit–risk ratio. Although the risks associated with situations were explained during telephone calls with physicians, it was not always easy to weigh up the benefits from a distance, without being present on the ward, and without an initial discussion with the patient’s care team.
PharmaCheck’s use in addition to CDSS for physicians
We used the final clinical PPV without a pharmacist’s intervention as a proxy measure of the impact PharmaCheck would have had if used as a standalone tool dedicated to physicians. Under these circumstances, a maximum of 14% of alerts would have been associated with a change in prescription. It is noteworthy that our approach assumes that every risk situation that led to a pharmaceutical intervention and a prescription modification would have been recognized as relevant by physicians and would have led to the same modifications. This optimistic assumption is consistent with results showing that using a CDSS for prescribing medication has a statistically significant positive effect on a physician’s practice performance. (50,51) The main benefits of using a CDSS were better quality prescriptions and lower rates of medication errors. Becke and al. supported this finding: they measured acceptance rates (i.e., prescription modification) varying between 14.0% and 90.0% for five alerts appearing as pop-ups on physicians’ digital interfaces during order entry. (52) Thus, one prospect for this system could be to adapt some of the PharmaCheck alerts to notify physicians as they are prescribing, particularly for those alerts whose final clinical PPVs with and without a pharmacist are similar. Finally, the only clinical rule fulfilling this criterion was digoxin combining a supra-therapeutic digoxinemia rate. For the other rules, the final clinical PPVs with a pharmacist were 1.3 to 67 times higher than without one. Thus, a large proportion of alerts would be deemed irrelevant and adherence to PharmaCheck would be compromised given the risk of alert fatigue if alerts were addressed exclusively to physicians. (36) Nevertheless, it should be noted that the clinical rules actively triggered when a caregiver consults the patient’s record at the time of prescription do not consider that the situation might evolve during hospitalization and require subsequent adjustment (before the patient file is consulted again). CDSSs like PharmaCheck enable continuous passive monitoring. Thus, the prescription of a direct oral anticoagulant initiated several days before, associated with a sudden and brutal deterioration of renal function, will trigger an alert as soon as the laboratory results are published.
Limitations
One of our study’s main limitations is the large number of alerts that were deemed irrelevant and for which no intervention was made (about 80% of alerts). As already discussed, one of the main reasons for this over-representation is related to the quality of the data related to patients’ problems (the second most common risk category) and the insufficient specificity of some clinical rules. The recent reconfiguration of the clinical rules in our EHR to take into account these structural problems will certainly solve some of them. (52) Moreover, PharmaCheck’s specificity could be improved by adjusting queries to consider several discriminating conditions, such as the addition of temporal and dynamic aspects (e.g., a sudden drop in renal function).
Another limitation is that the potential negative predictive values of the different clinical rules have not been assessed, as this would have created a heavy workload and required a manual chart review. However, except for patient problems, the triggers for PharmaCheck’s alerts are structured data (ATC codes, dosage values, biological analysis identifiers, etc.) that have been previously listed for query creation. Thus, these data are in our system permanently and we expect a low proportion of false-negative alerts.
PharmaCheck can identify high-risk situations at a distance from the prescriber, but it may take several hours each days for the pharmacist to check for alerts (PharmaCheck runs at a fixed time on weekdays), meaning the occurrence of adverse events remains possible. Indeed, PharmaCheck complements a system currently being deployed that is based on alerts sent to physicians as they are prescribing drugs. (53,54) An overall strategy will thus make it possible to consolidate prescription safety by combining multiple contextualized alerts, monitoring opportunities, and targeted healthcare professionals.