The International Journal of the Addictions, 14(7), 993-1000, 1979
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Research Note
The Validity and Reliability of Self-Reported Data from Heroin Addicts: Mailed Questionnaires Compared with Face-to-Face Interviews Richard N. Bale," Ph.D. Veterans Administration Medical Center Palo Alto, California 94304; Department of Psychiatry and Behavioral Sciences Stanford University School of Medicine Stanford, California 94305
Abstract
Immediately following receipt of their 1 -year follow-up mailed questionnaire, 55 former patients from an addiction treatment program were interviewed personally, and a urine sample was collected. Results indicate a high degree of correspondence of self-reported drug use with the urinalysis reports, and moderately *Address reprint requests to Richard N. Bale, Ph. D., Ward 323B4, Veterans Administration Medical Center, 3801 Miranda Avenue, Palo Alto, California 94304. 993 Copyright @ 1979 by Marcel Dekker, Inc. All Rights Reserved. Neither this work nor any part may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, microfilming, and recording, or by any information storage and retrieval system, without permission in writing from the publisher.
994
BALE
Subst Use Misuse Downloaded from informahealthcare.com by University of Melbourne on 11/26/14 For personal use only.
high correspondence between the information on employment, school attendance, legal status, and length of heroin run given in the mailed questionnaire with that provided in the personal interview. Most studies investigating the behavior of addicts in and out of treatment rely on self-reports. More objective data such as urinalyses, employment records, and arrest files are often difficult or impossible to obtain. Because there are compelling reasons for reporting sensitive information such as illicit drug use untruthfully, e.g., fear of legal sanctions or denial of further treatment, the validity of self-reported data is a crucial issue in interpreting results of evaluative studies. Outcome data are usually gathered by mail, phone, or in a personal (face-to-face) interview. The majority of locally funded or “in-house” evaluation efforts utilize questionnaires completed by mail or phone. Personal interviews, while much more expensive and thus generally limited to projects with substantial funding, are said to be preferred to mail or phone efforts because (1) the validity and reliability of the data is presumed to be greater, and (2) more complex and comprehensive data can be gathered, utilizing an interviewer’s special skills. As yet no study has investigated the validity of self-reported data from questionnaires completed by mail or phone, or compared such data with those gathered in a face-to-face interview. Previous reports of the validity of self-reported drug use have involved personal interviews. In a study of 59 Puerto Rican addicts who were former federal prisoners at Lexington, Ball (1967) reported that 5 of 7 subjects whose urines were found to be positive had admitted to heroin use in the interview (71% “truthful” responses). Another 18 subjects provided urines found negative for opiates; urine samples were not collected on the remaining 34 subjects who were either institutionalized (27), refused to provide a urine sample (3), or were “not feasible” (4). The only other study of the validity of selfreported drug use at the time of this writing was reported by Amsel and Mandell (1 976) who examined a sample of 1,500 former patients at the U.S. Public Health Hospital at Lexington or Ft. Worth. She reported that 74% of the self-reports of drug use matched the urinalysis results while another 14% reported no drug use but had a positive urine. Several problems are encountered in interpreting these data: the authors do not state the total percentage of subjects reporting no drug use, and a percentage of truthful responses is impossible to calculate; the type of drugs reported or tested for is not specified, and the collection rate of
SELF-REPORTED DATA FROM HEROIN ADDICTS
995
Subst Use Misuse Downloaded from informahealthcare.com by University of Melbourne on 11/26/14 For personal use only.
urines is quite low (only 267 of 865 respondents provided a specimen). The present study was designed to answer two questions. (1) Are addicts truthful when reporting their recent heroin use on a questionnaire completed by mail or phone? (2) How closely do other standard outcome data (on drug use, social productivity, and criminal behavior) gathered in such a format correspond with the same information obtained in a faceto-face interview?
METHOD Five hundred and eighty-five male veteran heroin addicts were admitted to an inpatient detoxification ward at the Veterans Administration Hospital in Palo Alto. These patients, about half of whom stayed for longer term treatment in methadone maintenance or a therapeutic community, were involved in a 2-year comprehensive outcome evaluation. The design of this study and preliminary results have been reported elsewhere (Bale, 1975; Bale et al., 1975, 1978, in press, a). One year follow-up by mailed questionnaire was completed on 568 (97.0%) of the study population. The questionnaires were completed by mail or phone by trained interviewers employed by Stanford University and not administratively connected to the VA treatment programs, and subjects understood that these data would remain confidential to the research staff. The methods used in the follow-up procedure have been documented elsewhere (Bale et al., 1977). For the purposes of this study the 216 questionnaires returned in the last half of the study period were considered. One hundred and three subjects were excluded who were either in residential treatment, in jail, or outside a 100-mile radius. Of the remaining sample of 113, a random sample of 55 was drawn. The demographic characteristics of the sample are presented in Table 1 . Following completion of the 1-year follow-up questionnaire by mail or phone, a trained interviewer made immediate contact with the subject to arrange a personal interview in order to “gather additional data.” All 55 interviews were completed, during which items in the original questionnaire were reassessed and a urine sample was obtained (no subject refused). Urine samples were analyzed a t the VA laboratory at Palo Alto by thin-layer chromotography and a confirming radioimmunoassay. The sensitivity of the described tests for clinical samples has been reported (Catlin et al., 1973).
BALE
996
Table 1 Demographic Characteristics of Sample (N = 55)
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Characteristics Mean age Ethnic background : White Black Mexican-American Other (Puerto Rican, Asian) Education: High school graduate or G.E.D. Some college Work : Working in 2 years preceding admission Months working in preceding 2 years Criminal activity: Arrested in 2 years preceding admission Marital status: Single Married Divorced or separated Treatment status: Detoxification only-VA system Longer term treatment in VA after detoxification
Number 31.5 years
20 (36%) 20 (36 %I 9 (16%) 6 (13%) 41 (75%) 20 (36%) 46 (84%) 10.9 months 30 (55 %)
23 (42%) 14 (25 %) 18 (33%)
33 (60%) 22 (40%)
R ES ULTS We compared the laboratory results of the collected urine specimens to the subject’s own reports of his drug use on the mailed questionnaire and in the subsequent interview (Table 2). Twenty-one of the 55 urines collected were positive for morphine (the metabolite and thus the indicator of heroin use). Of these 21, 18 (86%) had reported some frequency of heroin use “during the past month” on the mailed questionnaire, while three had indicated no heroin use during that period. Although it is possible that the three subjects had in fact not used heroin in the month period but had in just the few hours before the personal interview, we chose to interpret the results as untruthful responses. Interestingly, two of the three were currently on a methadone program and may have feared reprisals by the treatment staff in spite of assurances of confidentiality; these subjects did admit recent heroin use in the personal interview.
Subst Use Misuse Downloaded from informahealthcare.com by University of Melbourne on 11/26/14 For personal use only.
SELF-REPORTED DATA FROM HEROIN ADDICTS
997
Although 18 of the 21 subjects with positive urines had admitted some heroin use on the questionnaire, a fewer number, 16 (76%), admitted recent heroin use in the face-to-face interview. [This compares closely to the 71% truthfulness rate obtained by Ball (1967)l. Combining the two sources of information, 20 subjects (95%) with positive urines admitted some recent heroin use in either the mailed questionnaire or personal interview. Stated somewhat differently, the results indicate that 24 of the 27 subjects who indicated on the mailed questionnaire that they had used no heroin recently had negative urines (89% truthful) while 30 of the 35 subjects who declared no recent heroin use in the personal interview had negative urines (86% truthful). It should be noted from Table 2 that four subjects who reported heroin use in the past week had urines negative for morphine. It is possible that they had used weak or “bunk” heroin which would not show in the urinalysis; more likely, they had used too long a time period before the specimen was given for the analysis to pick up positive traces, and the evidence supports this interpretation. The four subjects with negative urine results reported heroin use ranging from 20 to 96 hours (mean of 59.0 hours) previous to the interview. The subjects with positive urines reported a range of zero to 24 hours, with a mean of 8.1 hours. We next investigated the correspondence of the mailed questionnaire Table 2 Validity of Reported Heroin Usen Frequency of heroin use during past month on mailed questionnaire
Urinalysis results for morphine (urine collected in subsequent personal interview) Positive
“Daily” “Several times/week” “Just a few times”
X, 0, 1, 1, 22, 16 X, 5, 12, 18, 24,4, 12 x, x, 1,20, 12
“Not at all”
x, 12, 11
Totals
21
Negative X, 72 48 96.20, X, X, X,
x, x x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x 34
Totals 8 8 12 27
55
.Figures in each cell represent the number of hours previous to the personal interview that each subject reported having used heroin. An “X” represents a subject who stated that he had used no heroin the week preceding the interview.
BALE
998
Table 3
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Correspondence o f Self-Report9
Length of longest heroin run in year Average salary during past 6 months Public assistance at 1 year Working at 1 year % in school in past 6 months % arrested in past 6 months % convicted in past 6 months % on probation at 1 year
Mailed questionnaire, mean or %
Personal interview, mean or %
Degree of exact correspondence of individual scores
3.09 months
3.33 months
t = .73, r = .76, p > .40 t = 1.47, r = .92,
$686
$744
$177
$175
50 % 25 % 33 % 15% 40 %
50 % 33 % 33 % 15% 36 %
p
> .10
t = .32, r = .95, p > .50 93 %
78% a9 %
78 % 83 %
"For length of heroin run, salary, and public assistance, degree of correspondence is given as correlations between the scores and t tests for correlated means. For school, arrests, convictions, and probation data, the degree of correspondence is the percentage of subjects reporting an event who indicated so in both the questionnaire and the personal interview.
data with data on similar items gathered in a personal interview. Seven variables were compared: length of longest heroin run during the past year, salary, amount of current public assistance funds, school attendance, arrests, convictions, and legal status. The results are summarized in Table 3. The results indicate a very high degree of correspondence between the mailed questionnaires and personal interviews for the group percentages and means, across all seven major outcome variables. The degree of correspondence between the two formats for individual subjects is less but still moderately high (78 to 93% rates of exact correspondence and correlations between .76 and .95). The data do not differ significantly for questionnaires completed by phone when compared to those completed by mail for any outcome variable.
DISCUSSION Under conditions specified, results from mailed questionnaires on standard outcome variables corresponded very highly with those gathered
Subst Use Misuse Downloaded from informahealthcare.com by University of Melbourne on 11/26/14 For personal use only.
SELF-REPORTED DATA FROM HEROIN ADDICTS
999
in the more expensive effort of a personal interview. Moreover, the validity of self-reported heroin use on mailed questionnaires was equal to or greater than that obtained in a personal interview. These conclusions are cautiously offered because of the methodological limitations of the study. Specifically, the questionnaire period pertains to a month-long period while the personal interview data pertain to an immediately subsequent period. A central assumption underlying our findings is that most subjects using heroin during a month-long period will continue to use in the subsequent week, and that most not using will also continue not to use. It should be further noted that on other variables besides heroin use we have only reported on the correspondence of data between the two sources and not on the validity or accuracy (when compared with more objective records) of either set of data. What the results do suggest is that, for a few standard outcome variables, the data collected in relatively inexpensive mailed questionnaires are likely to be quite similar to those collected in personal interviews, although the faceto-face contact may be desirable when more complex information is required. It is posible that the high level of validity found is related to the fact that the subjects knew that they were part of a serious research study conducted by research personnel separate from and not providing individual data to the clinical staff. That is, they knew that the information they provided would not affect their past relationships with clinical staff or their future contact with the treatment programs (a realistic concern for many who made subsequent contact with the hospital). It is unclear what the validity of the self-reported data on drug use might have been had the subjects thought that the information would be conveyed to the clinical staff. Finally, it should be noted that the discrepancies between the questionnaire and interview data are not accounted for by a few subjects; in actuality, 47 subjects had discrepant reports on at least one variable. This result lends support to the notion that discrepancies reflect memory or estimation errors more than a determination on the part of some patients to inaccurately report data. Alternatively, subjects may be differentially sensitive to various outcome data on their functioning, purposely reporting some data inaccurately while truthful on others. In a later report we will examine the relationship of truthfulness in selfreporting to subject characteristics and time in treatment (Bale et al., in press, b).
1000
BALE
ACKNOWLEDGMENTS
Subst Use Misuse Downloaded from informahealthcare.com by University of Melbourne on 11/26/14 For personal use only.
This study was supported in part by grant DA-00384 from the National Institutes on Drug Abuse. Janet D. Brown, M.A., was responsible for the special follow-up for validity purposes, and L. Susan Cabrera, M.A., coordinated the overall follow-up effort. REFERENCES AMSEL, Z., MANDELL, W., MATTHIAS, L., MASON, C., and HOCHERMAN, I. Reliability and validity of self-reported illegal activities and drug use collected from narcotics addicts. Int. J. Addict. 1 l(2): 325-336, 1976. BALE, R.N. What we need to know. In V. P. Zarcone, Drug Addicts in a Therapeutic Community: The Satori Approach. Baltimore: York Press, 1975. BALE, R.N., CABRERA, L.S., and BROWN, J.D. Follow-up evaluation of drug abuse treatment. Am. J. Drug Alcohol Abuse 4(2): 233-249, 1977. BALE, R.N., VAN STONE, W.W., KULDAU, J., ENGELSING, T.M.J., ELASHOFF, R.M., and ZARCONE, V.P. Therapeutic communities vs methadone maintenance. A prospective controlled study of narcotic addiction treatment: Design and first year follow-up results. Arch. Gen. Psychiatry in press, a. BALE, R.N., VAN STONE, W.W., KULDAU, J., ENGELSING, T.M.J., and ZARCONE, V.P. Preliminary two year follow-up results from a randomized comparison of methadone maintenance and therapeutic communities. In D. E. Smith (ed.) A Multicultural View of Drug Abuse. Cambridge, England: Hall, 1978, pp. 433-441. BALE, R.N., VAN STONE, W.W., KULDAU, J., ENGELSING, T.M.J., and ZARCONE, V.P. The validity of self-reported drug use. Int. J. Addict. in press, b. BALL, S.C. The reliability and validity of interview data obtained from 59 narcotic addicts. Am. J . Sociol. 72: 650-654, 1967. CATLIN, D.H., CLEELAND, R., and GRUNBERG, E. A sensitive, rapid radioimmunoassay for morphine and immunologically related substances in urine and serum. J . Clin. Chem. 216-220, 1973.
Subst Use Misuse Downloaded from informahealthcare.com by University of Melbourne on 11/26/14 For personal use only.
Research Note
The Validity and Reliability of Self-Reported Data from Heroin Addicts: Mailed Questionnaires Compared with Face-to-Face Interviews Richard N. Bale," Ph.D. Veterans Administration Medical Center Palo Alto, California 94304; Department of Psychiatry and Behavioral Sciences Stanford University School of Medicine Stanford, California 94305
Abstract
Immediately following receipt of their 1 -year follow-up mailed questionnaire, 55 former patients from an addiction treatment program were interviewed personally, and a urine sample was collected. Results indicate a high degree of correspondence of self-reported drug use with the urinalysis reports, and moderately *Address reprint requests to Richard N. Bale, Ph. D., Ward 323B4, Veterans Administration Medical Center, 3801 Miranda Avenue, Palo Alto, California 94304. 993 Copyright @ 1979 by Marcel Dekker, Inc. All Rights Reserved. Neither this work nor any part may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, microfilming, and recording, or by any information storage and retrieval system, without permission in writing from the publisher.
994
BALE
Subst Use Misuse Downloaded from informahealthcare.com by University of Melbourne on 11/26/14 For personal use only.
high correspondence between the information on employment, school attendance, legal status, and length of heroin run given in the mailed questionnaire with that provided in the personal interview. Most studies investigating the behavior of addicts in and out of treatment rely on self-reports. More objective data such as urinalyses, employment records, and arrest files are often difficult or impossible to obtain. Because there are compelling reasons for reporting sensitive information such as illicit drug use untruthfully, e.g., fear of legal sanctions or denial of further treatment, the validity of self-reported data is a crucial issue in interpreting results of evaluative studies. Outcome data are usually gathered by mail, phone, or in a personal (face-to-face) interview. The majority of locally funded or “in-house” evaluation efforts utilize questionnaires completed by mail or phone. Personal interviews, while much more expensive and thus generally limited to projects with substantial funding, are said to be preferred to mail or phone efforts because (1) the validity and reliability of the data is presumed to be greater, and (2) more complex and comprehensive data can be gathered, utilizing an interviewer’s special skills. As yet no study has investigated the validity of self-reported data from questionnaires completed by mail or phone, or compared such data with those gathered in a face-to-face interview. Previous reports of the validity of self-reported drug use have involved personal interviews. In a study of 59 Puerto Rican addicts who were former federal prisoners at Lexington, Ball (1967) reported that 5 of 7 subjects whose urines were found to be positive had admitted to heroin use in the interview (71% “truthful” responses). Another 18 subjects provided urines found negative for opiates; urine samples were not collected on the remaining 34 subjects who were either institutionalized (27), refused to provide a urine sample (3), or were “not feasible” (4). The only other study of the validity of selfreported drug use at the time of this writing was reported by Amsel and Mandell (1 976) who examined a sample of 1,500 former patients at the U.S. Public Health Hospital at Lexington or Ft. Worth. She reported that 74% of the self-reports of drug use matched the urinalysis results while another 14% reported no drug use but had a positive urine. Several problems are encountered in interpreting these data: the authors do not state the total percentage of subjects reporting no drug use, and a percentage of truthful responses is impossible to calculate; the type of drugs reported or tested for is not specified, and the collection rate of
SELF-REPORTED DATA FROM HEROIN ADDICTS
995
Subst Use Misuse Downloaded from informahealthcare.com by University of Melbourne on 11/26/14 For personal use only.
urines is quite low (only 267 of 865 respondents provided a specimen). The present study was designed to answer two questions. (1) Are addicts truthful when reporting their recent heroin use on a questionnaire completed by mail or phone? (2) How closely do other standard outcome data (on drug use, social productivity, and criminal behavior) gathered in such a format correspond with the same information obtained in a faceto-face interview?
METHOD Five hundred and eighty-five male veteran heroin addicts were admitted to an inpatient detoxification ward at the Veterans Administration Hospital in Palo Alto. These patients, about half of whom stayed for longer term treatment in methadone maintenance or a therapeutic community, were involved in a 2-year comprehensive outcome evaluation. The design of this study and preliminary results have been reported elsewhere (Bale, 1975; Bale et al., 1975, 1978, in press, a). One year follow-up by mailed questionnaire was completed on 568 (97.0%) of the study population. The questionnaires were completed by mail or phone by trained interviewers employed by Stanford University and not administratively connected to the VA treatment programs, and subjects understood that these data would remain confidential to the research staff. The methods used in the follow-up procedure have been documented elsewhere (Bale et al., 1977). For the purposes of this study the 216 questionnaires returned in the last half of the study period were considered. One hundred and three subjects were excluded who were either in residential treatment, in jail, or outside a 100-mile radius. Of the remaining sample of 113, a random sample of 55 was drawn. The demographic characteristics of the sample are presented in Table 1 . Following completion of the 1-year follow-up questionnaire by mail or phone, a trained interviewer made immediate contact with the subject to arrange a personal interview in order to “gather additional data.” All 55 interviews were completed, during which items in the original questionnaire were reassessed and a urine sample was obtained (no subject refused). Urine samples were analyzed a t the VA laboratory at Palo Alto by thin-layer chromotography and a confirming radioimmunoassay. The sensitivity of the described tests for clinical samples has been reported (Catlin et al., 1973).
BALE
996
Table 1 Demographic Characteristics of Sample (N = 55)
Subst Use Misuse Downloaded from informahealthcare.com by University of Melbourne on 11/26/14 For personal use only.
Characteristics Mean age Ethnic background : White Black Mexican-American Other (Puerto Rican, Asian) Education: High school graduate or G.E.D. Some college Work : Working in 2 years preceding admission Months working in preceding 2 years Criminal activity: Arrested in 2 years preceding admission Marital status: Single Married Divorced or separated Treatment status: Detoxification only-VA system Longer term treatment in VA after detoxification
Number 31.5 years
20 (36%) 20 (36 %I 9 (16%) 6 (13%) 41 (75%) 20 (36%) 46 (84%) 10.9 months 30 (55 %)
23 (42%) 14 (25 %) 18 (33%)
33 (60%) 22 (40%)
R ES ULTS We compared the laboratory results of the collected urine specimens to the subject’s own reports of his drug use on the mailed questionnaire and in the subsequent interview (Table 2). Twenty-one of the 55 urines collected were positive for morphine (the metabolite and thus the indicator of heroin use). Of these 21, 18 (86%) had reported some frequency of heroin use “during the past month” on the mailed questionnaire, while three had indicated no heroin use during that period. Although it is possible that the three subjects had in fact not used heroin in the month period but had in just the few hours before the personal interview, we chose to interpret the results as untruthful responses. Interestingly, two of the three were currently on a methadone program and may have feared reprisals by the treatment staff in spite of assurances of confidentiality; these subjects did admit recent heroin use in the personal interview.
Subst Use Misuse Downloaded from informahealthcare.com by University of Melbourne on 11/26/14 For personal use only.
SELF-REPORTED DATA FROM HEROIN ADDICTS
997
Although 18 of the 21 subjects with positive urines had admitted some heroin use on the questionnaire, a fewer number, 16 (76%), admitted recent heroin use in the face-to-face interview. [This compares closely to the 71% truthfulness rate obtained by Ball (1967)l. Combining the two sources of information, 20 subjects (95%) with positive urines admitted some recent heroin use in either the mailed questionnaire or personal interview. Stated somewhat differently, the results indicate that 24 of the 27 subjects who indicated on the mailed questionnaire that they had used no heroin recently had negative urines (89% truthful) while 30 of the 35 subjects who declared no recent heroin use in the personal interview had negative urines (86% truthful). It should be noted from Table 2 that four subjects who reported heroin use in the past week had urines negative for morphine. It is possible that they had used weak or “bunk” heroin which would not show in the urinalysis; more likely, they had used too long a time period before the specimen was given for the analysis to pick up positive traces, and the evidence supports this interpretation. The four subjects with negative urine results reported heroin use ranging from 20 to 96 hours (mean of 59.0 hours) previous to the interview. The subjects with positive urines reported a range of zero to 24 hours, with a mean of 8.1 hours. We next investigated the correspondence of the mailed questionnaire Table 2 Validity of Reported Heroin Usen Frequency of heroin use during past month on mailed questionnaire
Urinalysis results for morphine (urine collected in subsequent personal interview) Positive
“Daily” “Several times/week” “Just a few times”
X, 0, 1, 1, 22, 16 X, 5, 12, 18, 24,4, 12 x, x, 1,20, 12
“Not at all”
x, 12, 11
Totals
21
Negative X, 72 48 96.20, X, X, X,
x, x x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x 34
Totals 8 8 12 27
55
.Figures in each cell represent the number of hours previous to the personal interview that each subject reported having used heroin. An “X” represents a subject who stated that he had used no heroin the week preceding the interview.
BALE
998
Table 3
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Correspondence o f Self-Report9
Length of longest heroin run in year Average salary during past 6 months Public assistance at 1 year Working at 1 year % in school in past 6 months % arrested in past 6 months % convicted in past 6 months % on probation at 1 year
Mailed questionnaire, mean or %
Personal interview, mean or %
Degree of exact correspondence of individual scores
3.09 months
3.33 months
t = .73, r = .76, p > .40 t = 1.47, r = .92,
$686
$744
$177
$175
50 % 25 % 33 % 15% 40 %
50 % 33 % 33 % 15% 36 %
p
> .10
t = .32, r = .95, p > .50 93 %
78% a9 %
78 % 83 %
"For length of heroin run, salary, and public assistance, degree of correspondence is given as correlations between the scores and t tests for correlated means. For school, arrests, convictions, and probation data, the degree of correspondence is the percentage of subjects reporting an event who indicated so in both the questionnaire and the personal interview.
data with data on similar items gathered in a personal interview. Seven variables were compared: length of longest heroin run during the past year, salary, amount of current public assistance funds, school attendance, arrests, convictions, and legal status. The results are summarized in Table 3. The results indicate a very high degree of correspondence between the mailed questionnaires and personal interviews for the group percentages and means, across all seven major outcome variables. The degree of correspondence between the two formats for individual subjects is less but still moderately high (78 to 93% rates of exact correspondence and correlations between .76 and .95). The data do not differ significantly for questionnaires completed by phone when compared to those completed by mail for any outcome variable.
DISCUSSION Under conditions specified, results from mailed questionnaires on standard outcome variables corresponded very highly with those gathered
Subst Use Misuse Downloaded from informahealthcare.com by University of Melbourne on 11/26/14 For personal use only.
SELF-REPORTED DATA FROM HEROIN ADDICTS
999
in the more expensive effort of a personal interview. Moreover, the validity of self-reported heroin use on mailed questionnaires was equal to or greater than that obtained in a personal interview. These conclusions are cautiously offered because of the methodological limitations of the study. Specifically, the questionnaire period pertains to a month-long period while the personal interview data pertain to an immediately subsequent period. A central assumption underlying our findings is that most subjects using heroin during a month-long period will continue to use in the subsequent week, and that most not using will also continue not to use. It should be further noted that on other variables besides heroin use we have only reported on the correspondence of data between the two sources and not on the validity or accuracy (when compared with more objective records) of either set of data. What the results do suggest is that, for a few standard outcome variables, the data collected in relatively inexpensive mailed questionnaires are likely to be quite similar to those collected in personal interviews, although the faceto-face contact may be desirable when more complex information is required. It is posible that the high level of validity found is related to the fact that the subjects knew that they were part of a serious research study conducted by research personnel separate from and not providing individual data to the clinical staff. That is, they knew that the information they provided would not affect their past relationships with clinical staff or their future contact with the treatment programs (a realistic concern for many who made subsequent contact with the hospital). It is unclear what the validity of the self-reported data on drug use might have been had the subjects thought that the information would be conveyed to the clinical staff. Finally, it should be noted that the discrepancies between the questionnaire and interview data are not accounted for by a few subjects; in actuality, 47 subjects had discrepant reports on at least one variable. This result lends support to the notion that discrepancies reflect memory or estimation errors more than a determination on the part of some patients to inaccurately report data. Alternatively, subjects may be differentially sensitive to various outcome data on their functioning, purposely reporting some data inaccurately while truthful on others. In a later report we will examine the relationship of truthfulness in selfreporting to subject characteristics and time in treatment (Bale et al., in press, b).
1000
BALE
ACKNOWLEDGMENTS
Subst Use Misuse Downloaded from informahealthcare.com by University of Melbourne on 11/26/14 For personal use only.
This study was supported in part by grant DA-00384 from the National Institutes on Drug Abuse. Janet D. Brown, M.A., was responsible for the special follow-up for validity purposes, and L. Susan Cabrera, M.A., coordinated the overall follow-up effort. REFERENCES AMSEL, Z., MANDELL, W., MATTHIAS, L., MASON, C., and HOCHERMAN, I. Reliability and validity of self-reported illegal activities and drug use collected from narcotics addicts. Int. J. Addict. 1 l(2): 325-336, 1976. BALE, R.N. What we need to know. In V. P. Zarcone, Drug Addicts in a Therapeutic Community: The Satori Approach. Baltimore: York Press, 1975. BALE, R.N., CABRERA, L.S., and BROWN, J.D. Follow-up evaluation of drug abuse treatment. Am. J. Drug Alcohol Abuse 4(2): 233-249, 1977. BALE, R.N., VAN STONE, W.W., KULDAU, J., ENGELSING, T.M.J., ELASHOFF, R.M., and ZARCONE, V.P. Therapeutic communities vs methadone maintenance. A prospective controlled study of narcotic addiction treatment: Design and first year follow-up results. Arch. Gen. Psychiatry in press, a. BALE, R.N., VAN STONE, W.W., KULDAU, J., ENGELSING, T.M.J., and ZARCONE, V.P. Preliminary two year follow-up results from a randomized comparison of methadone maintenance and therapeutic communities. In D. E. Smith (ed.) A Multicultural View of Drug Abuse. Cambridge, England: Hall, 1978, pp. 433-441. BALE, R.N., VAN STONE, W.W., KULDAU, J., ENGELSING, T.M.J., and ZARCONE, V.P. The validity of self-reported drug use. Int. J. Addict. in press, b. BALL, S.C. The reliability and validity of interview data obtained from 59 narcotic addicts. Am. J . Sociol. 72: 650-654, 1967. CATLIN, D.H., CLEELAND, R., and GRUNBERG, E. A sensitive, rapid radioimmunoassay for morphine and immunologically related substances in urine and serum. J . Clin. Chem. 216-220, 1973.
