International Journal for Quality in Health Care 15:235-240 (2003)
© 2003 International Society for Quality in Health Care
Paper |
Assessing residents’ prescribing behavior in renal impairment
1Public Health Department, Groupe Hospitalier Pitié Salpêtrière et Faculté de médecine Pitié Salpêtrière (Paris VI), Paris
2Nephrology Department, Groupe Hospitalier Pitié Salpêtrière et Faculté de médecine Pitié Salpêtrière (Paris VI), Paris
3Epidemiology and Biostatistics Department, Hôpital Bichat et Faculté de Médecine Xavier Bichat (Paris VII), Paris, France
4Unité INSERM U444, France
Objective. Although fitting orders to renal function avoids overdosage and therefore iatrogenic risk, dosage adjustment is rarely made. The objective of this study was to assess residents’ prescribing behavior in renal impairment, through a standardized simulated clinical setting.
Method. This criterion-referenced study was carried out in a French teaching hospital. The hospital had 118 residents; 71 of them were asked to complete a questionnaire including four vignettes, simulating drug prescription in four ‘patients’ with various degrees of renal impairment (16 orders). The patients had an order of gentamicin sulfate, diclofenac sodium, and amlodipine bensylate. For each drug, the resident could maintain the order, discontinue the order, or change the dosage. A fourth drug, enalapril maleate, was to be started, with three possible dosages and the possibility of not prescribing it. The reference chosen for assessment was the Vidal dictionary, which corresponds to the Physician’s Desk Reference and is the French reference for prescription.
Results. All the residents approached for the survey accepted the offer to complete the questionnaire. Among the 16 simulated orders, the median number of appropriate orders per resident was nine. Considering the renal function of their patients, 62% of residents wrote an inappropriate order for gentamicin, 42% wrote an inappropriate order for diclofenac, and 52% wrote an inappropriate order for enalapril. Although no adjustment to renal function was required, 28% of the residents decreased the dosage of amlodipine and ordered an underdose.
Conclusion. Considering the iatrogenic risk related to the lack of dosage adjustment, attention should be drawn to increasing residents’ awareness of dosage adjustment in renal impairment and to providing them with better information on patients’ renal function.
Keywords: dosage adjustment, renal impairment, residents prescribing, vignettes
Dosage adjustment according to renal function decreases iatrogenic risk and irreversible renal impairment [1]. Although recommended for many drugs, these adjustments are rarely made [2,3]. According to the Leape classification, the lack of adaptation may result from lack of knowledge of the drug, including: (1) underestimation of the iatrogenic risk related to decreased drug elimination in mild renal impairment; and (2) ignorance of the medications that require a dosage adjustment in renal impairment [4–6]. It may also result from a poor estimation of the renal function of the patient. Changes in glomerular filtration rate should be estimated by the clearance of creatinine calculated using the Cockcroft and Gault formula [7]. In daily routine, glomerular filtration is determined from the measurement of serum creatinine, which has severe limitations. For example, if a patient develops acute renal failure and the glomerular filtration rate falls from 100 to 10 ml/min, the serum creatinine level will not change within 24 hours, until it reflects its accumulation in the plasma. In addition, an apparently minor increase in serum creatinine can reflect a marked fall in glomerular filtration rate (Figure 1). For that reason, the estimation of glomerular filtration rate through the calculation of creatinine clearance is mandatory in every patient.
|
Although the necessity of dosage adjustment is probably underestimated in clinical practice, few studies have considered this issue in hospitalized patients and the means to improve the use of medications in renal impairment [2,3,5,8]. Measuring the competence of physicians and the quality of their actual practice has proven to be difficult and problematic. Because they control for case mix, vignettes or written cases simulations allow assessment among different providers and between organizations that may care for different populations of patients under different systems of care. They have been described as a valid way of assessing quality of care [9–12].
The objective of this study was to assess residents’ prescribing behavior in ‘patients’ with renal impairment, through a standardized simulated clinical setting using hypothetical vignettes.
Methods
Design and setting
This prospective criterion-referenced survey described residents’ practice through clinical vignettes, a valid and comprehensive method of assessing quality of care and one that is able to control adequately for case-mix variation [12]. A questionnaire was distributed in May 2000 to the residents who assumed new positions in the Hospital Pitié Salpêtrière (Assistance Publique, Hôpitaux de Paris), a 2070-bed, tertiary care teaching hospital. This hospital has all major surgical and medical activities, with 40 in-patient departments, including 114 units, and >70 000 patients hospitalized every year. The hospital receives residents in all the medical and surgical departments.
Questionnaire
The questionnaire included two questions exploring the concerns of residents about dosage adjustment in renal impairment: (1) ‘Do you consider that the need for dosage adjustment in renal impairment is a frequent problem in hospital prescription?’; and (2) ‘From what level of serum creatinine should you check if the drugs prescribed may need dosage adjustment?’.
It also included four clinical vignettes (Table 1), simulating drug prescription in patients with various degrees of renal impairment. These drugs had been chosen in collaboration with a nephrologist and a pharmacist as they are frequently prescribed in general practice, or are well known to need adjustment in renal impairment (such as gentamicin), such that residents from medical or surgical departments might prescribe them regularly.
|
The data provided were patient’s age, gender, weight, and serum creatinine level. Creatinine clearance, which is not assessed directly in daily practice, was not provided in the survey, but could be calculated. Patients 1 and 3 had severe renal impairment, with similar calculated creatinine clearances (25 and 28 ml/min, respectively) but markedly different creatinine levels (1.2 and 2.2 mg/dl, respectively). Patients 2 and 4 had a creatinine level of 1.0 mg/dl, with, respectively, mild renal impairment (calculated clearance of 57 ml/min) and slight renal impairment (calculated clearance of 64 ml/min).
The patients were supposed to have just arrived in the department with the following order: (1) gentamicin sulfate 1 mg/kg three times a day; (2) diclofenac sodium 50 mg twice a day; (3) amlodipine bensylate 10 mg per day. The resident was to ratify each patient’s order or to change the dosage (with a choice between reducing the concentration or volume required per dose, or increasing the dosing interval). Another option was to discontinue the order. A fourth drug, enalapril maleate, was to be started, in the context of high blood pressure, with three possible dosages and the possibility of not prescribing it. We considered the initial prescription of enalapril before further adjustment, which could have been made according to enalapril titration.
Gold standard
The reference chosen for assessment was the 1999 edition of the Vidal dictionary [13].This dictionary pools the manufacturers’ summaries of product characteristics. Annually updated, it is officially distributed by the French Regulatory Authorities. It corresponds to the Physician’s Desk Reference and is the French reference for prescription. Commonly consulted by physicians, it may be used as formal evidence in legal procedures.
Participants and data
In French hospitals, residents change departments every 6 months during the 2–5 years of their residency. The study took place at the hospital administration office, where the residents come to register at the start of the semester.
An investigator was present at the administration office to deliver the questionnaire to the residents. They completed this anonymous questionnaire alone and returned it immediately to the investigator. The investigator specified that the purpose of the study was not to test the knowledge of the residents, but to comprehend their behavior when prescribing drugs in renal impairment. Residents were encouraged to act as they would for genuine patients, and to check any document they would use for usual prescribing, but not more. A Vidal dictionary was placed in an obvious position near the investigator, and was available for consultation if the residents requested it. Residents were also told to spend the same time on the questionnaire as they would actually take to write orders.
Analysis
A descriptive analysis of data was made. According to the calculated clearance of creatinine, the appropriateness of the 16 orders was determined (four medications and four patients’). The number of appropriate orders per residents was determined (range 0–16). A chi-square test of association was used to compare the frequency of inappropriate orders, with respect to: (1) whether or not an adjustment was required; (2) patient 1 versus patient 3—similar clearances but different serum creatinine levels; and (3) patient 1 versus patient 2—similar levels of serum creatinine and different renal function.
To take into account multiple testing, significance was set at P = 0.01 instead of P = 0.05.
Results
Among the 118 residents, 71 (60% of the residents) came to register at the hospital administration office at the beginning of the semester. All completed the questionnaire. Of these, 73% were medical residents, 3% were residents in anesthesia, and 24% had a surgical speciality. Fifty percent had already performed at least six postgraduate semesters, with seniority ranging from postgraduate semester 1 to 10 (out of 10).
The necessity of dosage adjustment in renal impairment was considered to be a frequent problem in hospital prescription by 85% of the residents (n = 58).
Among the residents, 20% (n = 13) reported checking if the dosage needs adjustment when serum creatinine is >0.9 mg/dl, 35% (n = 23) when creatinine is >1.2 mg/dl, 35% (n = 23) when creatinine is >1.7 mg/dl, and 6% (n = 4) when creatinine is >2.3 mg/dl. Four percent of the residents (n = 3) reported checking if the dosage needs adjustment for any level of serum creatinine.
Among the 16 simulated orders, the median number of appropriate orders per resident was nine (range 0–15) (Table 2).
|
Prescription of gentamicin sulfate (Table 3)
|
For gentamicin sulfate, 62% of the respondents prescribed a dosage that was not appropriate. The lowest percentage of inappropriate orders was observed for patient 4 (26% of inappropriate orders), for whom the dosage did not require adjustment. The highest percentages of inappropriate orders were observed for patients 1 and 3 (78% and 79% of inappropriate orders, respectively), for whom the dosage needed adjustment.
When the order needed to be modified (patients 1, 2, and 3), inappropriate orders were written more often than when no adjustment was required (74% versus 26%; P < 10-4).
For similar clearances (patients 1 and 3), the prescription of gentamicin was stopped more frequently in the patient with the highest levels of serum creatinine (40% for 2.2 mg/dl creatinine versus 20% for 1.2 mg/dl; P = 0.009).
For similar levels of serum creatinine (1.2 and 1.0 mg/dl), there was no difference in the proportion of residents who reduced the dosage of gentamicin (28% for patient 1 and 12% for patient 4, respectively; P > 0.01), although patient 1 had a severe renal impairment and patient 2 had a mild renal impairment. This dosage adjustment led to an overdose for patient 1, and to an underdose for patient 2.
Prescription of diclofenac sodium (Table 3)
For diclofenac sodium, 42% of the responders prescribed a dosage that was not adjusted to the renal function of their patients. The lowest percentage of inappropriate orders was observed for patient 4 (16% of inappropriate orders), for whom the dosage did not require adjustment. The highest percentage of inappropriate orders was observed for patient 1 (65% of inappropriate orders), whose order needed to be discontinued.
When the order required adjustment (patients 1 and 3), inappropriate orders were written more often than when no adjustment was needed (55% versus 29%; P = 10-3).
Considering patients with similar clearances, 55% of the residents discontinued the order of diclofenac for patient 3, who had the highest level of serum creatinine (2.2 mg/dl), compared with 35% of residents discontinuing the order for patient 1 (creatinine 1.2 mg/dl). Taking into account the correction for multiple tests, this difference is not significant (P = 0.02).
For similar levels of serum creatinine (1.2 and 1.0 mg/dl), there was no difference in the proportions of residents who reduced the dosage of diclofenac (30% for patient 1 and 27% for patient 2, respectively; P > 0.05), although patient 1 had a severe renal impairment and patient 2 had a mild renal impairment. This dosage adjustment led to an overdose for patient 1, and to an underdose for patient 2.
Prescription of amlodipine bensylate (Table 3)
For amlodopine bensylate, 31% of the responders wrote an order that was not appropriate for the renal function of their ‘patients’. The lowest percentage of inappropriate orders was observed for patient 4 (21% of inappropriate orders), the highest percentage of inappropriate orders were observed for patient 3 (42% of inappropriate orders).
Although no dosage adjustment was required, 3% of the residents discontinued the medication and 28% decreased the dosage of amlodopine, which led to an underdose.
The proportion of residents who inappropriately modified the orders was similar when comparing (1) patient 1 with patient 3 (who have both severe renal impairment, but different levels of creatinine), and (2) patient 1 with patient 2 (who have severe and mild renal impairment, but similar levels of creatinine).
Prescription of enalapril maleate (Table 3)
For enalapril maleate, 52% of the responders prescribed a dosage that was not adjusted to the renal function of their patients. Although they adjusted the dosage, 13% and 9% of the residents still ordered an overdose for patients 1 and 3, respectively. For patients 2 and 4, 57% and 36% of the residents overadjusted the dosage, respectively, leading to an underdose.
Discussion
Medication misuse has frequently been reported and may cause iatrogenic complications, which is an important cause of morbidity and mortality in hospitalized patients [6,14–17]. This study revealed a lack of dosage adjustment for medications in patients with renal impairment. Although most residents in our hospital were aware of the necessity to adjust dosage in renal impairment, very few of them (5%) reported checking whether their order needed adjustment without an increase in serum creatinine. This result indicates that the residents do not calculate the clearance of creatinine for every patient and thus may underestimate the depth of renal impairment, since an apparently minor increase in serum creatinine can reflect a marked fall in glomerular filtration rate (Figure 1).
A limitation of the study is that although it is supposed to examine residents’ performance in their daily routine, the residents may have either increased awareness in a simulated prescribing situation or decreased their concern about fictitious patients. However, as demonstrated by Peabody, using vignettes is a relevant and valid method to assess quality of care, compared with chart abstraction and standardized patients [12]. Using vignettes allows assessment of the quality of care provided by a group of physicians, and controls for case mix. It appears to be a valid and comprehensive method that focuses directly on the process of care provided in actual clinical practice. The conclusions of surveys using vignettes, therefore, may more likely be generalizable than surveys performed in a population of patients.
The study took place at the hospital administration office, where the residents are supposed to come and register at the beginning of the semester, except for those who had already worked as residents or as students in the hospital. Since the policy of the hospital concerning medication prescribing and dosage adjustment is similar to that of the other teaching hospitals where the residents could have worked, we assumed that the non responders (mostly residents who had already worked in the hospital) would not differ from the responders with regards to their prescribing behavior. All the residents who came to the administration office completed the questionnaire.
The residents were told that their knowledge of the drugs was not being tested and were encouraged to act as they would in their daily routine. Thus, the Vidal dictionary was set on the table and the residents were free to consult it to complete the questionnaire. During data collection, investigators noted that residents rarely checked their orders in the Vidal dictionary and rarely calculated creatinine clearance. This observation was confirmed by the results of the study: there was no difference in the percentage of residents who reduced the dosage of gentamicin for patients 1 and 2, who had similar levels of serum creatinine (1.2 and 1.0 mg/dl, respectively). Yet this adjustment led to an overdose for patient 1, who actually had severe renal impairment, and to an underdose for patient 2, who had mild renal impairment. Similar results were observed for the prescription of diclofenac and confirm that most residents consider serum creatinine level as an indicator of renal function, instead of calculating creatinine clearance, neglecting patients’ age and weight.
In prescribing amlodipine bensylate, which required no adjustment, some residents inappropriately reduced the dosage Similarly, some residents prescribed the lowest dosage of enalapril maleate where a higher dose could have been ordered. (Since dose titration is commonly performed with this medication, residents were told that they had to start the treatment, i.e. to write the order before dose titration.) Thus, residents were particularly cautious in their orders, but inappropriately adjusted the treatment, risking underdosage, rather than consulting the Vidal dictionary.
To improve prescriptions in renal impairment, it would be necessary to implement actions to draw physicians’ attention to the importance of creatinine clearance and to provide them, at the time of prescription, with reminders of prescription guidelines in renal impairment. A systematic review of controlled studies has shown that among 14 studies assessing this issue, six revealed an actual impact of computerized prescription on quality of care [18]. Therefore, implementing computing systems with reminders at the time of prescription could be of great interest. The implementation of computing systems that screen for inappropriate dosage and provide reminders of prescription guidelines in renal impairment has already been reported, with a positive impact on the quality of medical orders [5,19–21].
Conclusions
Although residents believe that dosage adjustment is a frequent problem in hospitalized patients, most of those in our study did not properly determine the renal function of fictitious patients and did not seek information on adjusting dosages of medications that are metabolized or excreted by the kidney, or of nephrotoxic medications.
Considering the iatrogenic risk and irreversible renal impairment related to the lack of dosage adjustment, attention should be drawn to the need to increase residents’ awareness of dosage adjustment in renal impairment and to provide them with better information on their patients’ renal function.
Address reprint requests to L. Salomon, Unité d’Evaluation, Hôpital Louis Mourier, 178 rue des Renouillers, 92701 Colombes Cedex, France. E-mail: laurence.salomon{at}lmr.ap-hop-paris.fr 
Accepted for publication February 5, 2003.
References
- Alkhunaizi AM, Schrier RW. Management of acute renal failure: new perspectives. Am J Kidney Dis 1996; 28: 315–328.[Web of Science][Medline]
- CantuTG, Ellerbeck EF, Yun SW, Castine SD, Kornhauser DM. Drug prescribing for patients with changing renal function. Am J Hosp Pharm 1992; 49: 2944–2948.[Abstract]
- Wong NA, Jones HW. An analysis of discharge drug prescribing among elderly patients with renal impairment. Postgrad Med J 1998; 74: 420–422.
[Abstract/Free Full Text] - Drayer DE. Active drug metabolites and renal failure. Am J Med 1977; 62: 486–489.[CrossRef][Web of Science][Medline]
- Rind DM, Safran C, Phillip RS et al. Effect of computer-based alerts on the treatment and outcomes of hospitalised patients. Arch Intern Med 1994; 154: 1511–1517.
[Abstract/Free Full Text] - Leape LL, Bates DW, Cullen DJ et al. System analysis of adverse drug events. J Am Med Assoc 1995; 274: 35–43.
[Abstract/Free Full Text] - Cockcroft DW, Gault MH. Prediction of creatinine clearance from serum creatinine. Nephron 1976; 16: 31–41.[Web of Science][Medline]
- Preston SL, Briceland LL, Lomaestro BM, Lesar TS, Bailie GR, Drusano GL. Dosing adjustment of 10 antimicrobials for patients with renal impairment. Ann Pharmacother 1995; 29: 1202–1207.[Abstract]
- Yager J, Linn LS, Leake B, Gastaldo G, Palkowski C. Initial clinical judgment by internists, family physicians, and psychiatrists in response to patient vignettes. I. assessment of problems and diagnostic possibilities. Gen Hosp Psychiatry 1986; 8: 145–151.[CrossRef][Web of Science][Medline]
- Tait RC, Chibnall JT. Physician judgments of chronic pain patients. Soc Sci Med 1997; 45: 1199–1205.
- Colenda CC, Rapp SR, Leist JC, Poses RM. Clinical variables influencing treatment decisions for agitated dementia patients: survey of physician judgments. J Am Geriatr Soc 1996; 44: 1375–1379.[Web of Science][Medline]
- Peabody JW, Luck J, Glassman P, Dresselhaus TR, Lee M. Comparison of vignettes, standardized patients, and chart abstraction: a prospective validation study of 3 methods for measuring quality. J Am Med Assoc 2000; 283: 1715–1722.
[Abstract/Free Full Text] - Vidal Dictionary. The Vidal Editions: Paris, 1999.
- Bates DW, Cullen DJ, Laird N et al. Incidence of adverse drug events and potential adverse drug events. Implications for prevention. ADE Prevention Study Group. J Am Med Assoc 1995; 274: 29–34.
[Abstract/Free Full Text] - Leape LL. Error in medicine. J Am Med Assoc 1994; 272: 1851–1857.
[Abstract/Free Full Text] - Lesar TS, Briceland L, Delcoure K, Parmalee JC, Masta-Gornic V, Pohl H. Medication prescribing errors in a teaching hospital. J Am Med Assoc 1990; 263: 2329–2334.
[Abstract/Free Full Text] - Brennan TA, Leape LL, Laird NM et al. Incidence of adverse events and negligence in hospitalized patients. Results of the Harvard Medical Practice Study I. N Engl J Med 1991; 324: 370–376.[Abstract]
- Hunt DL, Haynes RB, Hanna SE, Smith K. Effects of computer-based clinical decision support systems on physician performance and patient outcomes: a systematic review. J Am Med Assoc 1998; 280: 1339–1346.
[Abstract/Free Full Text] - Peterson JP, Colucci VJ, Schiff SE. Using serum creatinine concentrations to screen for inappropriate dosage of renally eliminated drugs. Am J Hosp Pharm 1991; 48: 1962–1964.[Abstract]
- Goldberg DE, Baardsgaard G, Johnson MT, Jolowsky CM, Shepherd M, Peterson CD. Computer-based program for identifying medication orders requiring dosage modification based on renal function. Am J Hosp Pharm 1991; 48: 1965–1969.[Abstract]
- McMullin ST, Reichley RM, Kahn MG, Dunagan WC, Bailey TC. Automated system for identifying potential dosage problems at a large university hospital. Am J Health Syst Pharm 1997; 54: 545–549.
[Abstract/Free Full Text]
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  E. Sellier, I. Colombet, B. Sabatier, G. Breton, J. Nies, E. Zapletal, J.-B. Arlet, D. Somme, and P. Durieux Effect of Alerts for Drug Dosage Adjustment in Inpatients with Renal Insufficiency JAMIA, March 1, 2009; 16(2): 203 - 210. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 E. A van Dijk, N. R. Drabbe, M. Kruijtbosch, and P. A. De Smet Drug Dosage Adjustments According to Renal Function at Hospital Discharge Ann. Pharmacother., July 1, 2006; 40(7): 1254 - 1260. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||