Informed consent for a prescription drug: Impact of disclosed information on patient understanding and medical outcomes

249

Patient Education and Counseling, 15 (1990) 249-259 Elsevier Scientific

Publishers

Ireland

Ltd.

Informed Consent for a Prescription Drug: Impact of Disclosed Information on Patient Understanding and Medical Outcomes Kimberly

A. Quaid,

Ruth R. Faden,

Eileen P. Vining and John M. Freeman

The Johns Hopkins University School of Medicine, Baltimore, Maryland (U.S.A.) (Received August (Accepted

3rd, 1989)

December

5th, 1989)

Abstract

Introduction

Based on the two legal standards of informed consent currently in use, the Medical Practice Standard and the Reasonable Person Standard, two disclosures containing information about the risks and benefits of the anticonvulsant, Carbamazepine, were empirically derived. One of these two disclosures was randomly given to a sample of 39 seizure patients and the parents of pediatric seizure patients prescribed this drug. Subjects were interviewed either immediately after disclosure and at followup, or at followup only. The results provide no evidence for the hypothesized negative effects - anxiety, treatment refusal, reduced compliance and increased side effects - of providing patients with extensive disclosures about prescription drugs.

Recent shifts in social attitudes have resulted in a demand on the part of patients and their advocates for more information concerning their treatment and the options available to them. Access to this information has come to be viewed as a right, reflected in the legal doctrine of informed consent. The responsibility of physicians to provide information has come to be seen as a moral obligation [l].

Keywords: Informed consent; Medical ethics.

R.A. Quaid, Psychiatry.

PhD

is an Instructor

in the

Department

of

R.R. Faden, PhD is Professor at the Division of Health Policy. E.E. Vining, MD is Associate Professor at the Department of Pediatric Neurology. J.M. Freeman, MD is Professor at the Department of Neurology. 0738-3991/90/$03.50 Published and Printed

0 1990 Elsevier Scientific in Ireland

Publishers

Ireland

While the overall goal of informed consent is to provide patients with sufficient information about medical recommendations for them to make informed choices, the circumstances under which disclosure is required, and the criteria for determining the adequacy of the information provided, have been a subject of intense debate. One of the most common medical interventions, prescribing drugs, is frequently conducted without patient consent any whatsoever. A majority of physicians (53%), report that they do not usually obtain consent from their patients for prescriptions [2]. The fact that physicians do not obtain consent from their patients for drug treatment may have serious ramifications. A study done by Ltd.

250

the Commission on Medical Malpractice of the United States Department of Health, Education and Welfare indicates that drug related malpractice lawsuits account for 10% of all cases. A substantial number of those cases are due to a failure to warn patients of reasonably foreseeable side effects [3]. Accepting the fact that patients should be given information concerning the risks of prescriptions drugs begs the question of what to tell them. The United States Courts are divided on the duties of physicians to inform their patients with respect to informed consent. Currently, there exist two competing legal rules for disclosure, the Medical Practice Standard (MPS) and the Reasonable Person Standard (RPS). Courts upholding the Reasonable Person Standard adhere to the idea that a physician’s duty to inform should be measured from the patient’s point of view: a physician’s duty to inform is determined by a patient’s need for information with which to make an intelligent decision regarding proposed medical treatment. This position is supported by the moral principle of respect for autonomy which stipulates that one should respect the values and decisions of another. The majority of courts have supported the Medical Practice Standard and the physicians’ point of view: a physician’s duty to disclose information is limited to those risks physicians normally disclose. In traditional medical ethics, the actual content of this information is affected by two moral principles. The first is the principle of beneficence as presented in the Hippocratic view of a physician’s obligations. In its most general form, the principle of beneficience specifies a positive obligation to remove existing harms and to confer benefits on others. If information regarding treatment is considered beneficial to a patient, the principle of beneficence dictates that this information be given to patients. The second principle affecting the contents

of what it has been conventional for physicians to tell their patients is the principle of nonmaleficence. This principle states that it is wrong to intentionally inflict harm on another person. In the context of informed consent, this principle is embodied in the one legal exception to the requirement for informed consent, the doctrine of therapeutic privilege. According to this doctrine, information can be withheld if one can reasonably predict that this information may be harmful to the patient [4]. Thus, the information given to a patient can differ greatly depending upon the point of view adopted and the attending physician’s beliefs concerning the effects of this information. Research has shown that the disclosure practices of physicians regarding the risks of prescription drugs, when compared to the preferences of patients for information, are significantly different [5,6]. Patients prefer and detailed extensive disclosures, particularly regarding risks, and do not want to have to ask for this information [7-l 11. In contrast, physicians favor disclosing only those risks with a high probability of occurrence [5,6]. This difference of opinion regarding the disclosure of drug information to patients may reflect differing beliefs concerning the consequences of disclosure. Those in favor of extensive disclosures believe that giving patients information about the drugs prescribed for them would help them recall drug information, recognize side effects and improve compliance [ 12-141 as well as make them more comfortable [5]. Those reluctant to provide patients with detailed information believe that such disclosures may increase patients’ anxiety 1151, increase the incidence of side effects through suggestibility [ 16,171, diminish compliance and lead to the refusal of treatment [17,18]. This article presents new empirical data concerning these issues. In particular, this study examines giving patients detailed information

251

in the context of prescribing Carbamazepine, the drug of choice for a number of epileptic patients. The main question addressed is: What are the consequences of providing patients with detailed information about the risks and benefits of drug treatment? Methods Intervention Using the Physicians’ Desk Reference (PDR) [19], a questionnaire was compiled containing general information, benefits, risks and side effects of the anticonvulsant, This questionnaire, along Carbamazepine. with a letter explaining the purpose of the study and signed by the head of pediatric neurology, was sent to 27 neurologists affiliated with Johns Hopkins Hospital. These neurologists were asked “Do you routinely tell your patients, in lay terminology, about any of the following?” They were then

directed to simply check all those items that were routinely disclosed for a typical case of focal or partial seizures for which Carbamazepine was the drug of choice. The information included in the physicians questionnaire was rewritten into lay terminology to be presented to patients. Qualitative descriptions of risk, as well as quantitative estimates of their likelihood of occurrence, were included. This questionnaire was presented to the first ten patients, or parents of pediatric patients, sitting in the waiting room of the Johns Hopkins Hospital Seizure Clinic during clinic hours. Subjects were asked to indicate the items of information about Carbamazepine, identified only as Drug A, they would want to know before consenting to treatment. This procedure was intended as a quick replication of work previously done [5]. The results of this procedure are presented

Fig. 1. Percentage of patients and parents who want to be informed about the possible risks and side effects associated with Carbamazepine compared to percentage of neurologists who report that they disclose this information. RISKS AND SIDE EFFECTS OF CARBAMAZEPINE

10

0

20

30

40

50

60

70

80

90

100%

NEED FOR BLOODWORK?? APLASTIC ANEMlA ?? LEUKOPENlA ?? ABNORMAL LlVER FUNC;l;; ID ??

ALLERGIC RASHES ?? HEART FAILURE KIDNEY PROBLEMS DRUG RELATED MORTALIM SEDATION ?? DIZZINESS ?? NAUSEA AND VOMITING DIARRHEA/CONSTIPATION ACHING JOINTS BLURRED VlSlON ?? LOSS OF APPETITE UNIDENTIFIED COMPLICATIONS m ??RISKS

I: PATIENTS/PARENTS

AND SIDE EFFECTS CONWNED

0

= NEUROLOGISTS

IN MEDlCAL PRACTICE DISCLOSURE

252

in Fig. 1. Of the 27 neurologists contacted, 17 (62.9%), returned their questionnaires. The number of risk items checked as routinely disclosed ranged from 0 to 11. Any item diiclosed by 50% or more of the physicians replying was included in what was termed the

Table I.

“Medical Practice Standard”. The Medical Practice Standard (MPS) disclosure consisted of five benefits and nine risks and side effects. The number of risk items patients and parents wished to be told ranged from 13 to 23. Any item of information that was desired by

Benefits and risks disclosed based on the medical practice and reasonable person standards.

Benefits (1)” (2)’ (3)’ (4)’ (5)”

Carbamazepine is the drug of choice for the type of seizure you are experiencing Carbamazepine is as, or more, effective than other drugs on the market for controlling seizures Carbamazepine has been in use for over 10 years and a lot is known about it People taking Carbamazepine every day tend to feel less tired than people taking other seizure medications This drug is being recommended because if patients do not take medications to control their seizures, there may be negative, but unpredictable, consequences

Risks and side effects (1) The manufacturers of Carbamazepine and the FDA are very concerned about the effects of Carbamazepine on the blood and white cells that fight infection; these effects on the blood and white cells, though serious, are rare; we recommend blood tests once a month to monitor these changes (2) Aplastic anemia, in which the bone marrow that produces white blood cells is damaged is the most serious of these changes; this occurs in less than 1 out of 50,000 patients taking Carbamazepine (3) Another blood related change is called leukopenia; leukopenia is a decrease in the number of white blood cells which may make it harder for the body to fight infections; most physicians do not believe that this is serious; this problem occurs in approximately 10 out of 100 patients taking this drug and usually goes away with no ill effects; in 2 out of 100 patients, the problem may last longer but still does not appear to cause any difficulties (4) Another common blood related change is anemia; this is a reduction in the number of red blood cells which may make a person feel tired; this occurs in less than 5 out of 100 persons taking Carbamazepine; usually the blood goes back to normal when the drug is stopped (5) Allergic rashes can occur; they occur in 1 out of 100 patients taking Carbamazepine; they may be serious, but they are rarely fatal (6) Abnormalities of liver function have been reported, but they are considered very rare (7Y Serious side effects of the heart and blood vessels can occur; these include heart failure and heart attacks; they have occasionally been fatal (W Doctors estimate that death occurs in less than 1 out of 100,000 patients taking Carbamazepine (9Y Carbamazepine has been reported to cause problems with kidney and bladder function including kidney failure and an inability to urinate (1OY Aching joints, muscles and leg cramps have been reported. The following side effects are usually related to the amount of medication and how it is taken; they usually go away in time or when the medication is adjusted; 20-50% of patients taking Carbamazepine may have one or two of these problems; many patients will have none (1 ly (12)” (13)’ (14)b (15)b (16)b (17)b

Drowsiness may occur Dizziness and unsteadiness may occur Blurred vision may occur Nausea and vomiting may occur Loss of appetite may occur Diarrhea and constipation can occur There is the possibility that some patients may have side effects or complications that have not yet been identified

* Items contained in both the MPS and RPS disclosures. b Items contained in RPS disclosures only.

253

at least 50% of the patient and parent subjects was included in the Reasonable Person Standard disclosure. The Reasonable Person Standard disclosure consisted of five benefits and 17 risks and side effects associated with Carbamazepine. The information contained in the Medical Practice Standard disclosure was an exact subset of the information contained in the Reasonable Person Standard disclosure. this information was For disclosure, rewritten into lay terminology, and the probabilities for the occurrence of the risks and side effects were added based on estimates contained in the AMA Drug Evaluations [20] and on the clinical experience of the neurologists participating in the design of the study. The final disclosures contained both qualitative descriptions of risks and side effects as well as in many cases, quantitative estimates of the likelihood of their occurrence (see Table I). The Anxiety Adjective Checklist (AACL) [21] was also given to patients. This instrument is designed to measure state anxiety, changes in anxiety over short periods of time, rather than trait anxiety, which is assumed to

Table II.

characterize a person’s behavior in a variety of situations. Scores range from 0 to 21 with a high score indicative of higher anxiety. Design A modification of the Solomon Four Group Design [22] was used (see Table II). Randomization schedules were developed for each recruitment site using a random number table. Subjects were randomly assigned to receive either the MPS or RPS disclosure, and to be interviewed either immediately after disclosure and at followup, 4-6 weeks later (Time 1 and Time 2), or at their followup appointment only (Time 2 only). This design permits an examination of the immediate effects of disclosure at the time decisions need to be made, the effects of disclosure over time, and the effects of the interview itself. Hypotheses Based on the literature in this area, several predictions can be made. While more extensive information concerning the side effects of Carbamazepine may increase subjects’ perceptions of the riskiness of the drug [23] no one should refuse treatment on the basis of this information [ 17,241.

Research design.

Instruments

Time 1

Time 2

AACL Recall of risks and side effects

AACL Recall of risks and side effects Experienced side effects Compliance

Number of subjects at First interview Randomization

Second interview

MPS MPS”

8

5 9

RPS RPS”

7

6 8

Total

15

28

‘Interviewed at followup appointment only.

254

The two disclosure standards differ mainly in the amount of information about the more common, less serious, side effects. If information about the serious, though remote, side effects and complications is the major cause of anxiety [23], the groups should not differ in anxiety related to disclosed information. Subjects receiving more information are expected to recall a greater amount of information immediately after disclosure [25,26], although the amount recalled may be a smaller proportion of the total amount of information [27]. At followup, any significant effects for disclosure standard at Time 1 are expected to dissipate. No main effects for disclosure standard are expected for anxiety as measured by the AACL. Subjects being interviewed for the first time may be more anxious than subjects having their second interview. Any anxiety generated by the disclosed information at Time 1 is expected to be supplanted by anxiety associated with any problems materializing since the beginning of drug treatment. Those subjects reporting more side effects are expected to be more anxious. Previous research has shown that very little information concerning side effects is recalled over time [28]. No main effects for standard are predicted for the number of side effects recalled. The most crucial question to be answered concerns the effects of different amounts of information on the number of side effects reported at followup. No main effects for disclosure standard on the number of side effects reported are expected [ 12-141. However, those subjects receiving more information about the more common side effects are expected to attribute more of their reported side effects to Carbamazepine [ 17,291. Subjects interviewed twice may show a tendency to attribute more of their side effects to Carbamazepine due to the reinforcement received as a result of the first interview.

No differences between standard or interview are expected for self ratings of compliance, physicians’ ratings of compliance, or blood levels of Carbamazepine [12-141. Procedure After the physician made the decision to prescribe Carbamazepine for a patient, and before the patient was told anything about the physician consulted the the drug, randomization scheme. He or she then took the appropriate disclosure form and obtained informed consent from the patient to participate in the study. Once consent had been obtained, the physician read through the disclosure verbatim and answered any questions that arose. A random sample of this portion of the doctor/patient interaction was taped as a check for the content of the disclosure. After disclosure, those subjects randomized to be interviewed immediately (5-10 min after disclosure) were interviewed. Subjects to be interviewed at followup only were introduced to the investigator (K.Q.) at that time. All interviews were conducted in a private room in the clinic and were in the form of a structured interview. At followup, all subjects were interviewed before seeing their doctor. Subjects The study population included adult patients consenting for themselves and the parents of pediatric patients who consent to treatment for their children. The adult patients were drawn from the Johns Hopkins Hospital Adult Seizure Clinic. The sample of parents of pediatric seizure patients was drawn from the Johns Hopkins Hospital Pediatric Seizure Clinic and the University of Maryland Pediatric Seizure Clinic. These clinics serve patients from the neighborhoods of Baltimore, as well as patients referred from outside of the city and state. Subjects who were 18 years of age or older, who spoke English, and who had Carbamazepine pre-

255

The small number of subjects interviewed at this time limits the generalizations that can be made. Results at this time, however, were as predicted (see Table III).

scribed for themselves or for their children for the first time were eligible for this study. Over a period of 1 year, 46 subjects were identified as being eligible for the study. Three (6.6%) of the individuals who were asked to participate refused.

No differences between standard were found for anxiety as measured by the AACL. Subjects given more information about side effects recalled more t(13) = - 3.50, P < 0.01. Subjects having more education recalled a greater number of side effects (r = 0.66, P< 0.01). There was no significant difference in the proportions of information recalled, although the difference was in the opposite direction from that predicted by previous research. There was no significant difference in the number of false side effects attributed to Carbamazepine.

Fifteen subjects were interviewed at Time 1, immediately after their discussion with their physician and the disclosure of information. These subjects were predominantly white (800/o), and female (86.7%) and 33.3% were married. The mean age was 33.73 years (S.D. = 13.24), and the mean education was 12.13 years (S.D. = 2.77). There were five adult patients and 10 parents of pediatric patients. T-tests for independent groups indicated that there were no significant differences between these two groups for age or education.

Fifty percent of all risks and side effects recalled were judged to be serious by the subjects. A 2 x 2 chi square examining the MPS vs. the RPS disclosure and whether a subject considered a risk or side effect serious yielded a significant result x2 (1) = 6.42, P < 0.05. The phi coefficient was 0.3 1. Those receiving the RPS disclosure were more likely to say that any side effect or risk recalled was serious.

As a result of randomization procedures, eight of these subjects had been given the Medical Practice Standard and seven the Reasonable Person Standard. T-tests for independent groups indicated that there were no significant differences between these two groups on age, education, or length of seizure disorder.

Table III.

Scores for subjects at first interview immediately Disclosure

standard

Medical practice

Age Education No. side effects recalled No. false side effects attributed to Carbamazepine

“P< 0.01.

(IV = 8)

Reasonable

person (N = 7)

X

S.D.

X

S.D.

30.50 11.38 2.12

13.52 1.30 1.36

37.43 13.00 7.14

12.88 3.79 3.58”

1.00

1.07

1.57

X AACL

after disclosure.

7.50

S.E. 1.90

X 8.43

1.62 S.E. 1.56

256

Results: Time 2

Four subjects who had their first interview and 11 subjects who had agreed to participate in the study, had signed the consent form, and who had been randomly selected to receive their first interview at followup, did not return for subsequent appointments at the clinic. Attempts made to reach these subjects by telephone were unsuccessful. Twenty-eight subjects were interviewed at their first followup appointment. These subjects were predominantly white (75%) and female (78.6%), and nearly half were married (46.4%). The mean age was 35.57 (SD. = 10.93), and the mean education was 13.64 (SD. = 2.56). There were five adult patients and 23 parents of pediatric patients. As a result of the randomization procedures, 14 of these subjects had been given the Medical Practice Standard and 14 had been given the Reasonable Person Standard. Eleven subjects had their second interview at this time, and 17 their first. A series of 2 x 2 analyses of variance with Standard (MPS and RPS) and Interview (first or second) as the independent variables indicated that there were no significant differences between groups in education, length of seizure history or number of days since disclo-

Table IV.

sure. There was a marginally significant main effect of standard for age F(1,24) = 4.35, P < 0.05. Those subjects receiving the Reasonable Person Standard were somewhat older, with a mean of 39.71, as compared to 31.34 for those receiving the Medical Practice Standard. The following results were obtained using a 2 x 2 analysis of variance (see Table IV). There was no significant difference between disclosure standard for the number of side effects recalled at followup. Reported side effects were recorded by both the investigator (K.Q.) and the physician using identical questionnaires. These questionnaires consisted of open-ended probe questions and a checklist of side effects containing seventeen true and six false side effects not normally associated with Carbamazepine. In response to questioning by the investigator, subjects receiving the MPS were more likely than RPS subjects to say they had physical problems in the past month in answer to an open-ended question x2(1) = 9.67, P < 0.01. The phi coefficient was 0.73. This effect for disclosure standard did not hold when subjects were asked to report physical symptoms by their physician.

Scores for subjects at second interview. Disclosure standard Medical practice (N = 14)

Age Education No. side effects reported to experimenter No. side effects reported to physician No. side effects recalled

Reasonable person (N = 14)

X

S.D.

X

S.D.

31.34 13.07

9.85 2.40

39.71 14.21

10.69 2.66

2.00

2.25

2.00

1.88

1.43 2.29

1.83 1.64

1.14 3.57

1.46 2.71

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More importantly, however, there were no significant effects for disclosure standard on the number of side effects reported to either the physician or the interviewer. No significant difference between standard was found for the number of false side effects attributed to Carbamazepine. Having more education and taking a higher dosage of medication were significantly related to reporting a greater number of side effects to both the and to the physician. A investigator significant correlation was found between the number of side effects reported to the experimenter and anxiety at Time 2 (r = 0.37, P < 0.05) and between the number of side effects recalled at Time 2 and the number of side effects reported to the physician (r = 0.33, P< 0.05). Those reporting physical problems or side effects were also asked “What do you think caused this?” Subjects having their second interview were more likely to attribute the problems they mentioned to Carbamazepine x2(1) = 6.01, P < 0.05. However, there were no differences in attributions between the RPS and MPS subjects. Compliance was measured in three ways: a self rating on a compliance scale, a physician estimate of compliance using the same scale, and blood levels of Carbamazepine taken at the time of the followup interview. These three measures were not significantly correlated. The results of a 2 x 2 factorial analysis of variance indicated that there were no main effects for disclosure standard or interview and self ratings of for the physician compliance. A 2 x 2 factorial analysis of variance indicated that there were no main effects for disclosure standard or interview, nor were there significant interactions for recorded blood levels of Carbamazepine at followup. All measured blood levels were within the recommended therapeutic range of 6-10 pg/ml.

Discussion

The results of this study provide little support for the hypothesized negative effects of providing patients with extensive information about the risks and side effects of prescription drugs. Patients provided with more information about the risks and side effects of Carbamazepine were no more likely than patients provided with less information to be anxious, to refuse treatment, to be noncompliant, or to report drug side effects. Indeed, none of our patients appeared unduly anxious following the disclosure of information and none refused to take Carbamazepine on the basis of the information given. Subjects receiving more information did recall more facts immediately after disclosure. While the overall level of recall was low for all subjects in both conditions, subjects receiving the information based on the Reasonable Person Standard recalled a greater number of side effects. This finding argues against two criticisms of extensive disclosure the problem of information overload and diminished returns as the amount of information increases. Our subjects also did not attribute false side effects to Carbamazepine, providing no support for the argument that too much information could result in confusion or a global feeling that there are “a lot” of side effects without any knowledge of particulars. The amount of information given about side effects did appear to affect subjects’ understanding and perceptions of treatment in several ways. Subjects receiving the Reasonable Person Standard were more likely to say that a side effect they recalled was serious. If one conceptualizes the riskiness of a drug as a function of the number of side effects, their seriousness, and the probability of their occurrence, those subjects given more information about the side effects of Carbamazepine perceived the drug to be more risky. This result is consistent with the literature

258

showing that prescription drugs having more side effects are perceived as more risky [23]. Also consistent with the literature was the fact that despite this perception of riskiness, no one refused treatment [ 12,241. By the time of followup, no differences were found in the amount of information recalled. Thus, there were no long term gains in understanding to be attributed to the more detailed disclosure. However, from the perspective of informed consent, the central issue is the level of understanding at the time consent is solicited, and not how much information is retained over time. Subjects receiving the MPS disclosure were more likely to report experiencing physical symptoms in the past month when they were asked by the experimenter, but not when asked by their physician. As the experimenter was blind to which disclosure they had received, this result is unlikely to be due to experimenter bias. It is possible that those receiving the Medical Practice Standard had experienced a side effect about which they had not been told and were at a loss to interpret these symptoms as anything other than with which they were vague “problems” unwilling to bother their physician. Most importantly, subjects receiving the Reasonable Person Standard did not report more side effects than subjects receiving the briefer disclosure. It is possible that our failure to find a “suggestibility effect” is a function of our having relatively few adult patients as subjects. However, this result is consistent with the empirical literature addressing this issue [12,13]. Even if subjects who had been given more information regarding possible side effects reported a greater Table V.

number of side effects, one would have to examine whether the side effects reported were actually experienced and whether, as has been previously shown, informed patients are more willing to report side effects they do experience

P-4 * The number of side effects reported correlated with taking a bigger dose of Carbamazepine and having more education. The subjects ingesting a larger dose of Carbamazepine might be expected to experience a greater number of side effects. Subjects with more education may have remembered more of the information they had been told, and may have correctly recognized what they or their children were experiencing as side effects of the drug about which they had been told. There were no differences between disclosure standard in compliance and the three compliance measures did not appear to be related. The issue of compliance is a difficult one to ascertain through interview. Although subjects may have reported themselves as less compliant if they did not take the medication exactly as recommended by their physician, that the fact all blood levels of Carbamazepine were within therapeutic ranges indicates that subjects were at least taking close to the recommended doses. This study can be viewed as a pilot investigation of a controversial topic within the medical and pharmaceutical professions. While the results suggest that physicians need not be afraid of negative consequences arising as a result of giving patients extensive information about the drugs they prescribe (see Table V), the limitations of nonrandom sampling, small sample size, and possible bias due to loss of subjects at followup limit the

Implications for practice.

(1)

There is little evidence drugs

(2)

Patients given more information are likely to know more about their medications at the time they are prescribed, although term gains in knowledge are not to be expected Patients given more information about their medications may be better able to correctly recognize side effects should occur

(3)

to support

the hypothesized

negative

effects

of giving patient

extensive

information

about

prescribed long they

259

generalizability of these results. Nevertheless, the use of an experimental design and the effort to examine the actual content of physician’s disclosures are useful contributions to the literature in this area.

tion in patients 13

14

Acknowledgments 15

We thank Dr. Robert Fisher and Dr. Edward Gratz for their assistance in collecting data for this project. Mr. Paul Garber and Ms. Ann Harlow Sheppe provided technical assistance.

16

References

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6

7 8

9

10

11 12

President’s Commission for the Study of Ethnical Problems in Medicine and Biomedical and Behavioral Research: Making Health Care Decisions. U.S. Government Printing Office: Washington, DC, 1982, Vol. 1. Harris L et al: Views of informed consent and decisionmaking: parallel surveys of physicians and the public. In: Making Health Care Decisions. President’s Commission for the Study of Ethical Problems in Medicine and Biomedical and Behavioral Research. U.S. Government Printing Office, 1982, Vol. 2, p. 17. Department of Health Education and Welfare: Report of the Secretary’s Commission on Medical Malpractice (DHEW publication (OS) 73-89) U.S. Government Printing Office: Washington, DC, 1973. Faden RR, Beauchamp TL: A History and Theory of Informed Consent. Oxford University Press: New York, 1986. Faden RR, Becker C, Lewis C, Freeman J, Faden AI: Disclosure of information to patients in medical care. Medical Care 1981; 19: 718. Christensen JJ, Boyce WT, Harrell H, Gardener MM: Circumcision and informed consent: is more information always better? Medical Care 1987; 25: 856. Joubert P, Lasagna L: Patient package inserts I: nature, notions and needs. Clin Pharmacol Ther 1975; 18: 507. Benson H, Gordon L, Mitchell C, Place V: Patient education and intrauterine conception: a study of two package inserts. Am J Pub1 Health 1977; 67: 446. Mazis M, Morris LA, Gordon E: Patient attitudes about two forms of printed oral contraceptive information. Medical Care 1978; 16: 1045. Keown C, Slavic P, Lichtenstein S: Attitudes of physicians, pharmacists and laypersons towards seriousness and need for disclosure of prescription drug side effects. Health Psycho1 1984; 3: 1. Wallace LM: Informed consent to elective surgery: the therapeutic value? Sot Sci Med 1986; 22: 29. Myers ED, Calvert EJ: The effect of forewarning on the occurrence of side effects and discontinuance of medica-

17

19 20 21

22

23

24

25

26

27 28

29

on Amitriptyline.

Br J Psychiatry

1973;

122: 461. Myers ED, Calvert EJ: The effect of forewarning on the occurrence of side effects and discontinuance of medication in patients on Dothiepin. J Int med Res 1976; 4: 237. Myers ED, Calvert EJ: Knowledge of side effects and perseverance with medication. Br J Psychiatry 1978; 132: 526. Keown C, Slavic P, Lichtenstein S: Influence of information about side effects on perceived risk of prescription drugs. Report 81-7, Decision Research: Eugene, OR, 1981. Leader A: Side effect of obtaining informed consent. Can Med Assoc J 1986; 7: 101. Myers MG, Cairns JA, Singer J: The consent form as a possible cause of side effects. Clin Pharmacol Ther 1987; 42: 250. Rapp MS: Informed consent and phobias. Can Med Assoc J 1986; 135: 435. Physician’s Desk Reference, 37th edn. Oradell, NJ: Medical Economics, 1983. American Medical Association: AMA Drug Evaluations, 5th edn. Chicago, IL: AMA, 1983. Zuckerman M: The development of an affect adjective checklist for the measurement of anxiety. J Consult Psycho1 1960; 24: 457. Campbell DJ, Stanley JC: Experimental and QuasiExperimental Designs for Research. Houghton Mifflin: Boston, MA, 1963, p. 24. Keown C: Risk judgments and intention measures after reading about prescription drug side effects in the format of a patient package insert. J Consumer Affairs 1983; 17: 277. Fraser AG: Do patients want to be informed? A study of consent for cardiac catheterisation. Br Heart J 1984; 52: 468. Gotsch AR, Ligouri S: Knowledge, attitude, and compliance dimensions of antibiotic therapy with PPIs. Medical Care 1982; 20: 581. Pryse-Phillips W, Jardine F, Bursey F: Compliance with drug therapy by epileptic patients. Epilepsia 1982; 23: 269. Ley P, Spelman MS: Communication in an outpatient setting. Br J Sot Clin Psycho1 1%; 4: 114. Bergler JH, Pennington AC, Metcalfe M, Freis ED: Informed consent: how much does the patient understand? Clin Pharmacol Ther 1980; 27: 435. Morris LA, Kanouse DE: Informing patients about drug side effects. J Behav Med 1982; 5: 363.

Correspondence

to:

K.A. Quaid Indiana University School of Medicine Department of Medical Genetics 975 West Walnut Street Indianapolis IN 46202-5251, U.S.A.