Contraception
45:363-368,
ACCURACY
OF
RECALL
P. NischanI,
1992 OF USE OF AN INTRAUTERINE D.B.
Thomas'
DEVICE
and K. Ebelingl
Faculty of Medicine (Charite), Clinic for Oncology, Schumannstrasse 20-21, Humboldt University, O-1040 Berlin, Germany Fred Hutchinson Cancer Research Center, 1124 Columbia Street, Seattle, WA 98104,
USA
ABSTRACT Within a case-control study __ of the relationship . ^ . I between oral contraceptives and breast cancer, inrormation on other contraceptive practices, including use of an intrauterine device (IUD) was obtained through interviews of study subjects and from the records of gynaecologists. Information from these two sources was compared for 239 women who had ever used an IUD. The results showed that agreement on total duration, number of IUD episodes, and time since first and time since last IUD use was excellent. As approximately 75% of IUDs used were unknown, agreement on brands could not be investigated. Studies investigating the effects of individual types of IUDs should use physician records as an additional source of information.
INTRODUCTION Pelvic inflammatory disease has been investigated as a possible short-term adverse effect of the intrauterine device (IUD) (l), and cancers of the genital tract have been studied as possible long-term consequences (2,3). Retrospective studies rely largely on data from interviews, and the accuracy of recall could influence the results, particularly of studies of possible long-term consequences of IUD use. Harlow and Linet (4) have recently reviewed studies investigating recall of past medical exposures. Among the exposures mostly investigated are medications associated with female reproduction. The use of an IUD, however, has not yet been considered. This paper reports results of a comparison of data on IUD usage from interviews and physicians' records. Submitted Accepted
for publication for publication
Copyright
0
November February
26, 1991 11, 1992
7992 Butterworth-Heinemann
364
Contraception
METHODS This study was carried out within the German part (formerly German Democratic Republic = GDR) of the WHO Collaborative Study of Neoplasia and Steroid Contraceptives (5) which was designed as a multinational hospital-based case-control study to investigate the possible influence of steroid contraceptives on cancer risk at several sites (breast, uterus, ovary, liver). At this centre (6), cases were restricted to breast cancer newly admitted to the Central Institute of Cancer Research, Berlin, from November 1982 through June 1986 and born in 1930 or later. Approximately two controls per case, group matched on age, were selected from among women admitted to the ear, nose and throat, eye, orthopaedic and dermatologic wards of the Klinikum Berlin-Buch for conditions presumably not associated with steroid contraceptives. Data were obtained by interviews utilizing a German version of an original English questionnaire. Beside other known or suspected risk factors, complete information was sought for use of steroid contraceptives and IUDs as to periods of use and brand name. A calendar was used to assist in recall of periods of use. As to IUDs, photos or samples were not shown. Women who had used steroid contraceptives or IUDs, as well as those with prior breast or gynaecological operations or Pap smears, were asked to provide the names of all gynaecologists that they had consulted during their reproductive life. The gynaecologists were then sent a questionnaire to obtain detailed information on the items of interest. Of 502 eligible cases and 1316 controls selected for this study, 490 cases and 1223 controls were interviewed cases and 260 controls had ever used an IUD, (6). Sixty-one and records were obtained from the gynaecologists of 45 (73.8%) of these cases and 194 (74.6%) of these controls. The characteristics of IUD use analysed include total duration, times since first and last use, number of periods of IUD use and name of IUD used. Agreement between interviews and gynaecologists' records on IUD use was judged by the overall proportion of agreement and by means of weighted kappa (7) for categorical data or categorised continuous data. The degree of agreement beyond chance is characterized by different ranges of values for weighted kappa: values greater 0.75 indicate excellent, values between 0.40 and 0.75 good, and values below 0.40 poor agreement. The kappa statistic has been criticized when applied to continuous data (8), and the correlation coefficient therefore was also calculated for continuous variables. Unless otherwise stated, all analyses are based on data from cases and controls combined.
365
Contraception
RESULTS Table I shows the total duration of IUD use as reported by women and their gynaecologists. Agreement between these sources was within one month in 45% of the women. This increased to 80% for a difference of up to one used in Table I, agreement year. Based on the categories with weighted kappa=0.88. The correlation was excellent, coefficient (r=0.95) was highly statistically significant (p97
27 6 0 0 0
+ 4 subjects
excluded
13-36
37-60
5 41 5 0 0
0 9 37 3 1
61-96 0 1 3 32 4
297 0 0 1 5 55
due to WnknownW.
Regarding time since first IUD use, agreement was within one month for 49% of the women, and within one year for 79% of the subjects (Table II). Excluding current users, there was agreement within one month on time since last use in 60% of the subjects, and within one year in 80% (Table III). Again, there was excellent agreement between the two data sources with weighted kappa=0.87 for time since first IUD use and weighted kappa=0.85 for time since last IUD use. The correlation coefficients (r=0.96 in both instances) were highly statistically significant (pI45 -
44 5 0 0 0
37-96 6 79 4 2 1
97-120 0 2 24 3 1
121-144 0 1 5 11 5
>145 0 0 2 3 41
366
TABLE
Contraception
III.
Time (months) since last IUD use - comparison of interview data and gynaecologist record data
Physician record
Subjects+
97 + 140 subjects
5 -
Subjects 1
2
3
4
->5
176 9 0 0 0
7 33 2 0 0
1 0 5 1 0
0 1 2 1 0
0 0 0 0 1
Agreement on duration of use, times since first and last use, and number of periods of use did not vary by marital status, place of residence, age at interview, duration of IUD use and time since last use, nor significantly by subject status (case or control). In both cases and controls, agreement within one year on total duration was 80%, on time since first use in cases 86% and in controls 77% (p-0.25), on time since last use 71% and 81% (p-0.30), and on number of periods 93% and 90% Agreement on the name of the IUD (P-0.75), respectively.
367
Contraception
increased significantly for city: 26.2%), years 29.1%) and age (highest
with place of residence (highest of education (highest for 13+: for
45:363-368,
ACCURACY
OF
RECALL
P. NischanI,
1992 OF USE OF AN INTRAUTERINE D.B.
Thomas'
DEVICE
and K. Ebelingl
Faculty of Medicine (Charite), Clinic for Oncology, Schumannstrasse 20-21, Humboldt University, O-1040 Berlin, Germany Fred Hutchinson Cancer Research Center, 1124 Columbia Street, Seattle, WA 98104,
USA
ABSTRACT Within a case-control study __ of the relationship . ^ . I between oral contraceptives and breast cancer, inrormation on other contraceptive practices, including use of an intrauterine device (IUD) was obtained through interviews of study subjects and from the records of gynaecologists. Information from these two sources was compared for 239 women who had ever used an IUD. The results showed that agreement on total duration, number of IUD episodes, and time since first and time since last IUD use was excellent. As approximately 75% of IUDs used were unknown, agreement on brands could not be investigated. Studies investigating the effects of individual types of IUDs should use physician records as an additional source of information.
INTRODUCTION Pelvic inflammatory disease has been investigated as a possible short-term adverse effect of the intrauterine device (IUD) (l), and cancers of the genital tract have been studied as possible long-term consequences (2,3). Retrospective studies rely largely on data from interviews, and the accuracy of recall could influence the results, particularly of studies of possible long-term consequences of IUD use. Harlow and Linet (4) have recently reviewed studies investigating recall of past medical exposures. Among the exposures mostly investigated are medications associated with female reproduction. The use of an IUD, however, has not yet been considered. This paper reports results of a comparison of data on IUD usage from interviews and physicians' records. Submitted Accepted
for publication for publication
Copyright
0
November February
26, 1991 11, 1992
7992 Butterworth-Heinemann
364
Contraception
METHODS This study was carried out within the German part (formerly German Democratic Republic = GDR) of the WHO Collaborative Study of Neoplasia and Steroid Contraceptives (5) which was designed as a multinational hospital-based case-control study to investigate the possible influence of steroid contraceptives on cancer risk at several sites (breast, uterus, ovary, liver). At this centre (6), cases were restricted to breast cancer newly admitted to the Central Institute of Cancer Research, Berlin, from November 1982 through June 1986 and born in 1930 or later. Approximately two controls per case, group matched on age, were selected from among women admitted to the ear, nose and throat, eye, orthopaedic and dermatologic wards of the Klinikum Berlin-Buch for conditions presumably not associated with steroid contraceptives. Data were obtained by interviews utilizing a German version of an original English questionnaire. Beside other known or suspected risk factors, complete information was sought for use of steroid contraceptives and IUDs as to periods of use and brand name. A calendar was used to assist in recall of periods of use. As to IUDs, photos or samples were not shown. Women who had used steroid contraceptives or IUDs, as well as those with prior breast or gynaecological operations or Pap smears, were asked to provide the names of all gynaecologists that they had consulted during their reproductive life. The gynaecologists were then sent a questionnaire to obtain detailed information on the items of interest. Of 502 eligible cases and 1316 controls selected for this study, 490 cases and 1223 controls were interviewed cases and 260 controls had ever used an IUD, (6). Sixty-one and records were obtained from the gynaecologists of 45 (73.8%) of these cases and 194 (74.6%) of these controls. The characteristics of IUD use analysed include total duration, times since first and last use, number of periods of IUD use and name of IUD used. Agreement between interviews and gynaecologists' records on IUD use was judged by the overall proportion of agreement and by means of weighted kappa (7) for categorical data or categorised continuous data. The degree of agreement beyond chance is characterized by different ranges of values for weighted kappa: values greater 0.75 indicate excellent, values between 0.40 and 0.75 good, and values below 0.40 poor agreement. The kappa statistic has been criticized when applied to continuous data (8), and the correlation coefficient therefore was also calculated for continuous variables. Unless otherwise stated, all analyses are based on data from cases and controls combined.
365
Contraception
RESULTS Table I shows the total duration of IUD use as reported by women and their gynaecologists. Agreement between these sources was within one month in 45% of the women. This increased to 80% for a difference of up to one used in Table I, agreement year. Based on the categories with weighted kappa=0.88. The correlation was excellent, coefficient (r=0.95) was highly statistically significant (p97
27 6 0 0 0
+ 4 subjects
excluded
13-36
37-60
5 41 5 0 0
0 9 37 3 1
61-96 0 1 3 32 4
297 0 0 1 5 55
due to WnknownW.
Regarding time since first IUD use, agreement was within one month for 49% of the women, and within one year for 79% of the subjects (Table II). Excluding current users, there was agreement within one month on time since last use in 60% of the subjects, and within one year in 80% (Table III). Again, there was excellent agreement between the two data sources with weighted kappa=0.87 for time since first IUD use and weighted kappa=0.85 for time since last IUD use. The correlation coefficients (r=0.96 in both instances) were highly statistically significant (pI45 -
44 5 0 0 0
37-96 6 79 4 2 1
97-120 0 2 24 3 1
121-144 0 1 5 11 5
>145 0 0 2 3 41
366
TABLE
Contraception
III.
Time (months) since last IUD use - comparison of interview data and gynaecologist record data
Physician record
Subjects+
97 + 140 subjects
5 -
Subjects 1
2
3
4
->5
176 9 0 0 0
7 33 2 0 0
1 0 5 1 0
0 1 2 1 0
0 0 0 0 1
Agreement on duration of use, times since first and last use, and number of periods of use did not vary by marital status, place of residence, age at interview, duration of IUD use and time since last use, nor significantly by subject status (case or control). In both cases and controls, agreement within one year on total duration was 80%, on time since first use in cases 86% and in controls 77% (p-0.25), on time since last use 71% and 81% (p-0.30), and on number of periods 93% and 90% Agreement on the name of the IUD (P-0.75), respectively.
367
Contraception
increased significantly for city: 26.2%), years 29.1%) and age (highest
with place of residence (highest of education (highest for 13+: for
