Changing physician behavior in ordering digoxin assays

Educational intervention to improve appropriate digoxin therapeutic drug monitoring: a quasi-experimental study

OBJECTIVES

Our previous retrospecive study evaluating the appropriateness of serum digoxin concentration (SDC) measurements revealed errors in the timing of blood specimen collection in 98% of the tests. The aim of this study is to evaluate the appropriateness of the SDC measurements and the factors involved in inappropriate test-ordering, after training health personnel in digoxin therapeutic drug monitoring.

METHODS

This is a training-based quasi-experimental study. The residents and nurses of the Cardiology Clinic were trained first in December 2017, and refresher training courses were carried out every month throughout the study. The medical data of the inpatients receiving digoxin therapy were recorded prospectively, between January and December 2018. The appropriateness of the physicians' orders for SDC measurement was evaluated according to the criteria of the right indication and right timing of blood collection. The results are presented by descriptive statistics, Student's t-test and χ² analysis.

RESULTS

A total of 232 SDC tests were ordered for 121 patients (age: 71.0±12.6 years, 56.2% women). Of these orders,129 (55.6%) were considered appropriate: 205 (88.4%) for indication and 129 (62.9%) for blood collection timing. There was a significant correlation between inappropriate order for SDC test and the age of the patient, female gender, impairment of renal function tests, high levels of serum BNP and the number of medications used (P<0.005).

CONCLUSIONS

Approximately a one-half decrease in inappropriate tests compared with our previous study results imply that education has a positive effect on physician behaviour. However, physicians' concerns due to increased risk factors for the patient still play a role in inappropriate test-ordering.

Improving psychotherapeutic medication prescribing in Florida: implementation of the Florida Medicaid Drug Therapy Management Program (MDTMP)

This paper describes a program that was established by Florida Medicaid to improve the quality of prescribing of psychotherapeutic medications. It relates the process used for defining quality medication treatment including the definitions of unusual psychotherapeutic medication indicators (UPMI). It details the results of analysis of FY 2007-2008 pharmacy claims data using these indicators that enabled the Program to identify practices and prescribers that required targeted interventions. The most frequently triggered UPMI for adults involved the use of 2 or more antipsychotics for greater than 60 days; high doses of psychotherapeutic medications was the indicator most frequently triggered for children closely followed by the use of 2 or more antipsychotics for more than 45 days. Prescriptions that triggered UPMI were concentrated in a small number of prescribers. These results led to the Program focusing on these high frequency practices and on the prescribers most associated with them. They also led to the implementation of new quality improvement initiatives like the implementation of a psychiatric telephone consultation line for pediatricians who are treating children with serious emotional disturbances who do not have access to child psychiatrists.

Interrupted time series designs in health technology assessment: lessons from two systematic reviews of behavior change strategies

OBJECTIVES

In an interrupted time series (ITS) design, data are collected at multiple instances over time before and after an intervention to detect whether the intervention has an effect significantly greater than the underlying secular trend. We critically reviewed the methodological quality of ITS designs using studies included in two systematic reviews (a review of mass media interventions and a review of guideline dissemination and implementation strategies).

METHODS

Quality criteria were developed, and data were abstracted from each study. If the primary study analyzed the ITS design inappropriately, we reanalyzed the results by using time series regression.

RESULTS

Twenty mass media studies and thirty-eight guideline studies were included. A total of 66% of ITS studies did not rule out the threat that another event could have occurred at the point of intervention. Thirty-three studies were reanalyzed, of which eight had significant preintervention trends. All of the studies were considered "effective" in the original report, but approximately half of the reanalyzed studies showed no statistically significant differences.

CONCLUSIONS

We demonstrated that ITS designs are often analyzed inappropriately, underpowered, and poorly reported in implementation research. We have illustrated a framework for appraising ITS designs, and more widespread adoption of this framework would strengthen reviews that use ITS designs.

Use of Digoxin Monitoring in a Hospital Setting as an Essential Tool in Optimizing Therapy

Objective

To determine what triggers the use of digoxin therapeutic drug monitoring (TDM) that adheres to established indications and the change in digoxin dosage after the result of monitoring is obtained.

Methods

This prospective study included 86 patients admitted to 6 medicine wards and 2 intensive cardiac care unit wards in a tertiary-care center. Data on patients' demographics, drug therapy, serum chemistry values, indications for digoxin therapy, indications for ordering the drug assay, timing of the blood sample relative to administration of the last dose, and physicians' decisions after attaining serum digoxin concentrations were collected.

Results

Eighty-six digoxin assays were evaluated. Indications for the use of a digoxin assay were mostly routine without a clear indication (66%); in only 22% of the assays were orders considered clinically justified. Eleven patients had concentrations >2 ng/mL, but only 8 patients had digoxin intoxication. In only 31% of patients did the medical staff respond to the results. In only 21% of patients with subtherapeutic drug concentrations was there a change in digoxin dose.

Conclusions

Although there are clear indications for the use of digoxin TDM, physicians seem to routinely order these blood tests. The clinicians did not adequately use the digoxin concentration data to optimize therapy. The assistance of a clinical pharmacist or pharmacologist is warranted for use of the assays, to optimize digoxin therapy.

A case series of hospitalized patients with elevated digoxin levels

PURPOSE

Although there is renewed enthusiasm for the use of digoxin in patients with heart failure, current dosing guidelines are based on a nomogram published in 1974. We studied the incidence of and risk factors for elevated digoxin levels in patients admitted to a community hospital, and compared their dosage regimens to published guidelines.

SUBJECTS AND METHODS

We reviewed the charts of all patients who had serum digoxin levels greater than 2.4 ng/mL during a 6-month period. We collected demographic and clinical data, indications for digoxin use, digoxin dosage, concurrent medications, laboratory data, and clinical and electrocardiographic features of digoxin toxicity.

RESULTS

Of the 1,433 patients with digoxin assays, 115 (8%) patients had elevated levels. Of the 82 patients with complete records and correctly timed digoxin levels, 59 (72%) had electrocardiographic or clinical features of digoxin toxicity. Patients with serum digoxin levels >2.4 ng/mL were slightly older (78 +/- 8 versus 73 +/- 9 years of age; P = 0.12) and had greater serum creatinine levels (3.1 +/- 7.3 versus 1.4 +/- 0.3 mg/dL; P = 0.01) than those with levels < or =2.4 ng/mL. Forty-seven patients had elevated digoxin levels on admission, including 21 patients admitted for digoxin toxicity. Impaired or worsening renal function contributed to high levels in 37 patients, and a drug interaction was a contributory factor in 10 cases. Twenty (43%) of these patients were taking the recommended maintenance dose based on the scheme employed in the Digitalis Investigation Group study. Thirty-five patients developed high digoxin levels while in hospital. In 26 patients, this followed a loading dose of digoxin for the control of rapid atrial fibrillation. Impaired renal function was implicated in all of these patients. Despite the elevated digoxin level, rate control was achieved in only 11 patients of these patients.

CONCLUSIONS

Elevated digoxin levels and clinical toxicity remains a common adverse drug reaction. Elderly patients, particularly those with impaired renal function and low body weights, are at the greatest risk. As published digoxin nomograms often result in toxicity, clinical variables need to be monitored. In patients with congestive heart failure and normal sinus rhythm the potential benefit of digoxin is small; thus, patients should receive a dose that minimizes the risk of toxicity. For patients with new onset atrial fibrillation, other agents may be preferable for rate control.