Public Health (1991), 105, 69-78
((~ The Society of Public Health, 199l
The Completeness and Accuracy of Health Authority and Cancer Registry Records According to a Study of Ovarian Neoplasms A. K. Mukherjee ~, lan Leck 1, F.A. Langley 2 and Colin Ashcroft 3
Department of Public Health and Epidemio/ogy and 3Faculty of Medicine Computational Group, University of Manchester. 2Department of Pathology, St Mary's Hospital Manchester
The completeness and accuracy of Hospital Activity Analysis (HAA) and Regional Cancer Registry (RCR) records were investigated in a series of 868 histologically reviewed cases in which primary ovarian neoplasms had been diagnosed according to one or more of seven data sources including HAA and RCR. All the women concerned were residents of Manchester and Salford who had presented in 1979-83 aged 15 years or more. The histological review confirmed the diagnosis of ovarian neoplasia in 829 of these women and excluded it in 39. Among the 829 confirmed cases, 333 were malignant or of borderline malignancy and therefore eligible for registration with the RCR, and 496 were benign. Only 611 (74%) of the 829 cases were listed as ovarian neoplasms or cysts in HAA records of hospital admissions from the study area during the study period, and the HAA diagnosis was incorrect in 40% of the 611 listed cases. Among the 333 borderline or malignant cases, only 241 (72%) appeared among the RCR's registrations of ovarian neoplasms for the study period and area. The RCR record of histological diagnosis was inaccurate in over 20% of these 241 registered cases, although most of the inaccuracies did not affect whether the neoplasm was classified as borderline or malignant, Five per cent of the cases listed as ovarian neoplasms in the HAA file and 15% of those listed as registrable ovarian neoplasms by the RCR should not have been so listed. The findings highlight the limitations of these routine health information systems, both as sources of cases for research and as National Health Service management tools.
Introduction M u c h epidemiological research on cancer and planning o f cancer services relies o n the routine data on patients with malignant neoplasms and on hospital in-patient episodes o f all kinds, which in the U K are held by Regional Cancer Registries and Health Authorities respectively. Surprisingly few attempts to assess the completeness and accuracy o f these data have been reported, a l t h o u g h this is less true for the N o r t h Western Health Region o f England than for the c o u n t r y as a whole. Several years ago in this region, N w e n e and Smith ~ explored the completeness o f Regional Cancer Registry ( R C R ) records for several series o f cases ascertained f r o m other sources; Leck e t al. 2 examined the completeness and accuracy o f R C R records and o f the N o r t h Western Regional Health A u t h o r i t y ' s Hospital Activity Analysis ( H A A ) files for childhood neoplasms; and Benn, Leck and N w e n e 3 estimated the overall completeness o f cancer registration in the region. Correspondence: Prof. I. Leck, Department of Public Health and Epidemiology, University of Manchester, Stopford Building, Oxford Road, Manchester M 13 9PT.
70
A.K. Mukherjee et al.
Although the first and last of these three reports gave data on the completeness of RCR records for several specific types of adult cancer, data on the accuracy of these records, and on the completeness and accuracy of the cancer data in H A A files, were only published for childhood neoplasms. However, an opportunity, to enquire into the completeness and accuracy of H A A and RCR as sources of data on a group of both benign and malignant neoplasms in adults was provided by a recent study of the incidence of ovarian tumours in women aged 15 years and over in Manchester and Salford. The present paper describes this enquiry. Material and Methods
The primary source of data was the Manchester Ovarian T u m o u r Register (OTR), which records cases seen at hospitals in Manchester since 1974 and in the adjacent city of Salford since 1980, and has more recently come to include other districts also. The Register is maintained by the Manchester Ovarian T u m o u r Panel (OTP), consisting of consultants from all the hospital histopathology units in its catchment area. Each panel member is expected to circulate sections of all ovarian neoplasms examined in his or her unit to all other members of the Panel. The Panel meets every few weeks to assign a consensus diagnosis to each case from which sections have been circulated. The cases are then recorded in the OTR. The cases included in the present study were those diagnosed at ages of 15 years or more in 1979-83 in residents of Manchester, and in 1980--83 in Salford residents. They were classified according to a somewhat abbreviated version of the ovarian section of the International Histological Classification of Tumours. 4 This classifies neoplasms both by behaviour (benign, borderline and malignant) and by putative tissue of origin - the main categories of which are common 'epithelial', sex cord-stromal, germ cell and miscellaneous. Records of cases of ovarian neoplasms which satisfied the above criteria were also sought in six other data sources, as follows:
1. HAA files of the North Western and Mersey Regional Health Authorities. Throughout the study period, hospitals had been expected to complete an H A A record including identifying information and diagnosis for every in-patient at the end of his or her spell in hospital. These records had been coded locally and then sent as computer input to the Regional Health Authorities (RHAs). Diagnosis had been coded according to the 9th revision of the International Classification of Disease (ICD), 5 which distinguishes between only three categories of primary ovarian neoplasms - benign, malignant, and of uncertain behaviour (i.e. borderline), which are coded 220, 183 and 236.2 respectively. For the present study, the two RHAs supplied print-outs of the H A A records that appeared to relate to residents of the study area who had been admitted for in-patient treatment anywhere in the two regions during the study period, and who had been coded as having primary ovarian neoplasms or certain conditions which are liable to be confused with them - secondary ovarian malignancy, miscellaneous genito-urinary neoplasm, polycystic ovary, or other ovarian cyst (code n~)s. 198.6, 239.5, 256.4 and 620 respectively). 2. RCR records. These records relate to residents of the North Western Health Region with malignant neoplasms or neoplasms of uncertain malignancy who have attended hospital or died. Most of those treated at hospital are eventually notified voluntarily to the RCR by hospital medical records staff, whilst the national Office of Population Censuses and Surveys normally provides the RCR with transcripts of the certificates of cause of
Health Authority and Cancer Registry Records
71
death of residents if malignant neoplasia is mentioned there. When such a transcript is received in respect of a patient who has not been reported to the RCR by any hospital, further information is sought from the hospital where the patient was treated or from her GP. Diagnosis is coded not only by site, as in H A A records, but also according to the morphology code of the International Classification of Diseases for Oncology, 6 which codes histological appearance in enough detail for cases of ovarian tumours to be assigned to their appropriate categories in the classification used by the OTP. For the present study, the RCR supplied a listing of cases classified as cancer or neoplasms of uncertain malignancy of the ovary in residents of the study area for which the 'anniversary date' (defined as the date of first hospital treatment, or of first hospital admission or attendance in untreated cases) fell within the study period.
3. Death Certificates. The North Western R H A receives copies of all certificates of cause of death for residents of its region, and supplied a list of those which mentioned ovarian neoplasms.
4-6. Records" of necropsies, operations, and cytological examinations. At the hospitals in the study area, the necropsy reports and registers of gynaecological, general surgical and accident/emergency operations were searched for references to ovarian neoplasms, and reports of malignant cells of possible ovarian origin in ascitic or turnout fluid were sought in the registers of cytological examinations. The data on possible cases obtained from the above six sources were checked against those o f the OTR. If a patient was not recorded there, her hospital records were used to determine whether she was a member of the population covered by the study, except in the case of patients ascertained from H A A alone whose diagnosis was coded to 620 (simple ovarian cyst) in the International Classification of Disease. Because there were many such patients, the question whether it was worth checking for every one of them whether the correct diagnosis was ovarian neoplasm was explored by examining the hospital records of a 20% systematic sample; and as no cases o f ovarian neoplasms were found in this 20%, the remaining 80% with a diagnostic code of 620 were not considered further. In the case of each member of the study population who was not known to the O T R but had an ovarian neoplasm according to another source, an OTP member at the hospital which she had attended was asked to find any blocks of her ovarian tissue that had been prepared, and to circulate sections of this material to all other members of the OTP. The case was then reviewed by the OTP, and registered with the O T R if appropriate.
Results
The numbers of cases in members o f the study population which were ascertained from each source are shown in Table I. The first row of figures relates to cases yielded by the O T R - 685 in all. Spells of hospital in-patient care with a main or subsidiary diagnosis of ovarian neoplasms or cysts were recorded in t h e HAA files for the study period in 525 (77%) of these 685 cases; and in 203 (30%) an ovarian neoplasm had been registered with the R C R as presenting during the study period. The second, third and fourth rows of figures in Table I give the numbers of patients not known to the O T R who had ovarian neoplasms according to the other sources used. For each source and for all sources combined, these cases are broken down in the Table by
A.K. Mukherjee et al.
72
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Health Authority and Cancer Registry Records Table II
73
Completeness of HAA reporting of histologically confirmed ovarian neoplasms
HAA diagnosis
Primary ovarian neoplasm: Behaviour correctly recorded Behaviour incorrectly recorded Non-neoplastic ovarian cyst, or secondary ovarian or non-ovarian genital neoplasm Not found under above diagnoses in HAA
Number (% of n) by OTP diagnosis Benign neoplasm (n = 496)
Borderline neoplasm (n = 77)
Malignant neoplasm (n = 256)
Total (n = 829)
234 (47%) 22 (4%)
7 (9%) 33 (43%)
125 (49%) 18 (7%)
366 (44%) 73 (9%)
149 (30%)
7 (9%)
16 (6%)
172 (21%)
91 (18%)
30 (39%)
97 (38%)
218 (26%)
whether blocks of tissue from the affected ovary were available, and if so by whether examination by the O T P confirmed that a neoplasm was present. There were 340 such cases in all, including 183 for which blocks of tissue were obtained. Neoplasms were found in 144 (78.7%) of the latter 183 cases. These 144 cases were added to the 685 cases initially ascertained from the O T R to give a total of 829 histologically confirmed subjects for the present study. The true number of cases missed because blocks of tissue were not obtained for them may be crudely estimated by assuming that the proportion of true cases was the same for the 157 cases for which tissue blocks were not available as for the other 183 n o n - O T R cases. In this case, ovarian neoplasms would have been present in 78.7% (124 of the 157). Adding this figure of 124 to the number of histologically confirmed cases (829) gives an estimate of 953 for what the size o f the series would have been if tissue blocks had been available for all cases. The 829 cases studied amount to 87% of this estimate. Corresponding estimates for the individual sources are given on the last three rows of Table I. These estimates suggest that a m o n g all the true cases of neoplasms identified from H A A and R C R respectively, 97% and 84% were included in the study. Given that all the 829 cases studied had been in hospital with ovarian neoplasms during the study period, all should have had an H A A record with a main or subsidiary diagnosis of primary ovarian neoplasm. Table I! shows that according to the O T P this was only true of just over half the 829 cases, regardless of whether the neoplasms were of benign, borderline or malignant behaviour; and it was only in a minority of cases - a small minority in the borderline group - that the H A A record was correct, not only as to the presence of a neoplasm but also as to its behaviour. A m o n g the cases in which primary ovarian neoplasms were not recorded in H A A , a majority of those with benign neoplasms and small minorities of borderline and malignant cases were described in H A A as having ovarian cysts or in a few cases other genito-urinary neoplasms. The remainder had no H A A record of hospital admission with these conditions either. Another way of looking at the quality of H A A data is to consider what proportions of the diagnoses of ovarian neoplasms in H A A records were correct according to the OTP. Table III shows that the O T P reviewed 461 cases with such a diagnosis. In 79% of these cases, the H A A record was correct as to both the presence and the behaviour of a neoplasm; in 16% it was correct as to presence but not behaviour; and in 5% the O T P found no neoplasm. These figures largely reflect the distributions of the cases with H A A
A. K. Mukherjee et al.
74 Table III
Accuracy of HAA reports of ovarian neoplasms
OTP diagnosis
Primary ovarian neoplasm: Behaviour as in HAA Behaviour not as in HAA No primary ovarian neoplasm
Number (% of n) by HAA diagnosis Benign neoplasm (n = 273)
Borderline neoplasm (n = 28)
Malignant neoplasm (n = 160)
Total (n=461)
234 (86%) 26 (10%) 13 (5%)
7 (25%) 20 (71%) 1 (4%)
125 (78%) 27 (17%) 8 (5%)
366 (79%) 73 (16%) 22 (5%)
diagnoses of benign and malignant neoplasms; only in a quarter of the cases diagnosed as borderline neoplasms according to H A A was the diagnosis correct as to behaviour. The completeness and accuracy of the R C R data are examined in Tables IV VI. These tables relate only to cases which had borderline or malignant neoplasms according to the O T P or the R C R , since benign ovarian neoplasms are not eligible for R C R registration. Table IV shows that the O T P diagnosed borderline neoplasms in 77 and malignant neoplasms in 256 of the 829 study cases, and that 42% o f the borderline and 23% of the malignant cases had not been registered with the R C R by the time the list of R C R registrations was obtained (which happened between 26 and 27 months after the end of the study period). The behaviour recorded by the R C R for the registered cases was consistent with that agreed by the OTP whenever the O T P rating was malignant but only in just over three quarters of cases when it was borderline. The proportions of R C R registrations in which behaviour was recorded correctly according to the O T P are shown in Table V. Forty cases were registered as borderline and 243 as malignant, and the recording of behaviour was correct according to the O T P in over 80% of each of these groups. All those incorrectly registered as borderline were classified as benign by the OTP. O f those incorrectly registered as malignant, the O T P classified a quarter as borderline, a quarter as benign, and a half as having no primary ovarian neoplasm. The cases registered as borderline or malignant by the R C R included 241 which were also rated borderline or malignant by the OTP. In Table VI, the reliability of the R C R ' s
Table IV Completeness of RCR registration of histologically confirmed registrable ovarian neoplasms Number (% of n) by OTP diagnosis RCR status
Registered as ovarian neoplasm: Behaviour correctly recorded Behaviour incorrectly recorded Not registered as ovarian neoplasm
Total
Borderline neoplasm (n = 77)
Malignant neoplasm (n = 256)
(n = 333)
34 (44%) 11 (14%) 32 (42%)
196 (77%) o (0%) 60 (23%)
230 (69%) II (3%) 92 (28%)
Health Authority and Cancer Registry Records
75
Table V Accuracy of cancer registry reports as to reality and behaviour of ovarian neoplasms OTP diagnosis
Registrable (borderline or malignant) neoplasm: Behaviour as in RCR Behaviour not as in RCR Non-registrable (benign) neoplasm No primary ovarian neoplasm
Number (% of n) by RCR diagnosis Borderline neoplasm (n = 40)
Malignant neoplasm (n = 243)
Total (n = 283)
34 (85%) 0 (0%) 6 (15%) 0 (0%)
196 (81%) 11 (5%) 11 (5%) 25 (10%)
230 (81%) 11 (4%) 17 (6%) 25 (9°./0)
histological data for these cases has been explored by classifying each case according to the tissues from which the RCR registration and the OTP assessment implied that it might have arisen. The 241 cases included 182 which were common 'epithelial' in origin according to the RCR - an assessment which was confirmed by the OTP in 97% of these cases. There was much less agreement about the remaining 59 cases: 59% of them (15% of all cases) fell into the RCR miscellaneous group but were classified as common 'epithelial' by the OTP, and the R C R record was also inconsistent with the OTP finding in a further 19% of the 59. Discussion
HAA and cancer registration records proved less complete sources o f diagnostic data in this study than might have been expected from previous work. Ovarian tissue from all the women in the study had been removed during the study period, implying that these women had undergone in-patient treatment then which should have generated HAA records for all 829 of them and R C R records for the 333 with borderline or malignant neoplasms. However, HAA records of ovarian cysts or neoplasms were only found for 74% of the 829 (Table II) and R C R records were only found for 72% of the 333 (Table IV). By contrast, H A A and R C R records were each found for more than 90% of cases eligible for cancer registration in an investigation in which methods comparable to those of the present study were used to study childhood neoplasms in the N o r t h Western Health Region in the early 1970s. 2 Studies in which three different methods were used to assess the completeness of cancer registration at all ages also suggest that during the 1970s the RCR's records were more than 90% complete. 1"3 None of these earlier studies yielded figures to compare with the OTP's finding that 15% of the cases that were entered as registrable primary ovarian neoplasms at the RCR, and 5% of those with diagnoses of ovarian neoplasms in HAA files, should not have been so recorded (Tables V and III). Among possible reasons for the H A A and R C R listings used in the present study being less complete than previous studies would lead one to expect, a deterioration in the completeness of H A A and RCR records seems a much less likely explanation than that some records which should have been printed out on these lists were omitted because they had been wrongly attributed to places of residence outside the study area or to dates of presentation outside the study period. Support for this view is provided by studies elsewhere in which the frequency o f errors was 8% for local authority area of residence and 0.6% for date of hospital admission in HAA records 7, and 2% for area of residence and
A.K. Mukherjee et al.
76
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c~ 0 0
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((~ The Society of Public Health, 199l
The Completeness and Accuracy of Health Authority and Cancer Registry Records According to a Study of Ovarian Neoplasms A. K. Mukherjee ~, lan Leck 1, F.A. Langley 2 and Colin Ashcroft 3
Department of Public Health and Epidemio/ogy and 3Faculty of Medicine Computational Group, University of Manchester. 2Department of Pathology, St Mary's Hospital Manchester
The completeness and accuracy of Hospital Activity Analysis (HAA) and Regional Cancer Registry (RCR) records were investigated in a series of 868 histologically reviewed cases in which primary ovarian neoplasms had been diagnosed according to one or more of seven data sources including HAA and RCR. All the women concerned were residents of Manchester and Salford who had presented in 1979-83 aged 15 years or more. The histological review confirmed the diagnosis of ovarian neoplasia in 829 of these women and excluded it in 39. Among the 829 confirmed cases, 333 were malignant or of borderline malignancy and therefore eligible for registration with the RCR, and 496 were benign. Only 611 (74%) of the 829 cases were listed as ovarian neoplasms or cysts in HAA records of hospital admissions from the study area during the study period, and the HAA diagnosis was incorrect in 40% of the 611 listed cases. Among the 333 borderline or malignant cases, only 241 (72%) appeared among the RCR's registrations of ovarian neoplasms for the study period and area. The RCR record of histological diagnosis was inaccurate in over 20% of these 241 registered cases, although most of the inaccuracies did not affect whether the neoplasm was classified as borderline or malignant, Five per cent of the cases listed as ovarian neoplasms in the HAA file and 15% of those listed as registrable ovarian neoplasms by the RCR should not have been so listed. The findings highlight the limitations of these routine health information systems, both as sources of cases for research and as National Health Service management tools.
Introduction M u c h epidemiological research on cancer and planning o f cancer services relies o n the routine data on patients with malignant neoplasms and on hospital in-patient episodes o f all kinds, which in the U K are held by Regional Cancer Registries and Health Authorities respectively. Surprisingly few attempts to assess the completeness and accuracy o f these data have been reported, a l t h o u g h this is less true for the N o r t h Western Health Region o f England than for the c o u n t r y as a whole. Several years ago in this region, N w e n e and Smith ~ explored the completeness o f Regional Cancer Registry ( R C R ) records for several series o f cases ascertained f r o m other sources; Leck e t al. 2 examined the completeness and accuracy o f R C R records and o f the N o r t h Western Regional Health A u t h o r i t y ' s Hospital Activity Analysis ( H A A ) files for childhood neoplasms; and Benn, Leck and N w e n e 3 estimated the overall completeness o f cancer registration in the region. Correspondence: Prof. I. Leck, Department of Public Health and Epidemiology, University of Manchester, Stopford Building, Oxford Road, Manchester M 13 9PT.
70
A.K. Mukherjee et al.
Although the first and last of these three reports gave data on the completeness of RCR records for several specific types of adult cancer, data on the accuracy of these records, and on the completeness and accuracy of the cancer data in H A A files, were only published for childhood neoplasms. However, an opportunity, to enquire into the completeness and accuracy of H A A and RCR as sources of data on a group of both benign and malignant neoplasms in adults was provided by a recent study of the incidence of ovarian tumours in women aged 15 years and over in Manchester and Salford. The present paper describes this enquiry. Material and Methods
The primary source of data was the Manchester Ovarian T u m o u r Register (OTR), which records cases seen at hospitals in Manchester since 1974 and in the adjacent city of Salford since 1980, and has more recently come to include other districts also. The Register is maintained by the Manchester Ovarian T u m o u r Panel (OTP), consisting of consultants from all the hospital histopathology units in its catchment area. Each panel member is expected to circulate sections of all ovarian neoplasms examined in his or her unit to all other members of the Panel. The Panel meets every few weeks to assign a consensus diagnosis to each case from which sections have been circulated. The cases are then recorded in the OTR. The cases included in the present study were those diagnosed at ages of 15 years or more in 1979-83 in residents of Manchester, and in 1980--83 in Salford residents. They were classified according to a somewhat abbreviated version of the ovarian section of the International Histological Classification of Tumours. 4 This classifies neoplasms both by behaviour (benign, borderline and malignant) and by putative tissue of origin - the main categories of which are common 'epithelial', sex cord-stromal, germ cell and miscellaneous. Records of cases of ovarian neoplasms which satisfied the above criteria were also sought in six other data sources, as follows:
1. HAA files of the North Western and Mersey Regional Health Authorities. Throughout the study period, hospitals had been expected to complete an H A A record including identifying information and diagnosis for every in-patient at the end of his or her spell in hospital. These records had been coded locally and then sent as computer input to the Regional Health Authorities (RHAs). Diagnosis had been coded according to the 9th revision of the International Classification of Disease (ICD), 5 which distinguishes between only three categories of primary ovarian neoplasms - benign, malignant, and of uncertain behaviour (i.e. borderline), which are coded 220, 183 and 236.2 respectively. For the present study, the two RHAs supplied print-outs of the H A A records that appeared to relate to residents of the study area who had been admitted for in-patient treatment anywhere in the two regions during the study period, and who had been coded as having primary ovarian neoplasms or certain conditions which are liable to be confused with them - secondary ovarian malignancy, miscellaneous genito-urinary neoplasm, polycystic ovary, or other ovarian cyst (code n~)s. 198.6, 239.5, 256.4 and 620 respectively). 2. RCR records. These records relate to residents of the North Western Health Region with malignant neoplasms or neoplasms of uncertain malignancy who have attended hospital or died. Most of those treated at hospital are eventually notified voluntarily to the RCR by hospital medical records staff, whilst the national Office of Population Censuses and Surveys normally provides the RCR with transcripts of the certificates of cause of
Health Authority and Cancer Registry Records
71
death of residents if malignant neoplasia is mentioned there. When such a transcript is received in respect of a patient who has not been reported to the RCR by any hospital, further information is sought from the hospital where the patient was treated or from her GP. Diagnosis is coded not only by site, as in H A A records, but also according to the morphology code of the International Classification of Diseases for Oncology, 6 which codes histological appearance in enough detail for cases of ovarian tumours to be assigned to their appropriate categories in the classification used by the OTP. For the present study, the RCR supplied a listing of cases classified as cancer or neoplasms of uncertain malignancy of the ovary in residents of the study area for which the 'anniversary date' (defined as the date of first hospital treatment, or of first hospital admission or attendance in untreated cases) fell within the study period.
3. Death Certificates. The North Western R H A receives copies of all certificates of cause of death for residents of its region, and supplied a list of those which mentioned ovarian neoplasms.
4-6. Records" of necropsies, operations, and cytological examinations. At the hospitals in the study area, the necropsy reports and registers of gynaecological, general surgical and accident/emergency operations were searched for references to ovarian neoplasms, and reports of malignant cells of possible ovarian origin in ascitic or turnout fluid were sought in the registers of cytological examinations. The data on possible cases obtained from the above six sources were checked against those o f the OTR. If a patient was not recorded there, her hospital records were used to determine whether she was a member of the population covered by the study, except in the case of patients ascertained from H A A alone whose diagnosis was coded to 620 (simple ovarian cyst) in the International Classification of Disease. Because there were many such patients, the question whether it was worth checking for every one of them whether the correct diagnosis was ovarian neoplasm was explored by examining the hospital records of a 20% systematic sample; and as no cases o f ovarian neoplasms were found in this 20%, the remaining 80% with a diagnostic code of 620 were not considered further. In the case of each member of the study population who was not known to the O T R but had an ovarian neoplasm according to another source, an OTP member at the hospital which she had attended was asked to find any blocks of her ovarian tissue that had been prepared, and to circulate sections of this material to all other members of the OTP. The case was then reviewed by the OTP, and registered with the O T R if appropriate.
Results
The numbers of cases in members o f the study population which were ascertained from each source are shown in Table I. The first row of figures relates to cases yielded by the O T R - 685 in all. Spells of hospital in-patient care with a main or subsidiary diagnosis of ovarian neoplasms or cysts were recorded in t h e HAA files for the study period in 525 (77%) of these 685 cases; and in 203 (30%) an ovarian neoplasm had been registered with the R C R as presenting during the study period. The second, third and fourth rows of figures in Table I give the numbers of patients not known to the O T R who had ovarian neoplasms according to the other sources used. For each source and for all sources combined, these cases are broken down in the Table by
A.K. Mukherjee et al.
72
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Health Authority and Cancer Registry Records Table II
73
Completeness of HAA reporting of histologically confirmed ovarian neoplasms
HAA diagnosis
Primary ovarian neoplasm: Behaviour correctly recorded Behaviour incorrectly recorded Non-neoplastic ovarian cyst, or secondary ovarian or non-ovarian genital neoplasm Not found under above diagnoses in HAA
Number (% of n) by OTP diagnosis Benign neoplasm (n = 496)
Borderline neoplasm (n = 77)
Malignant neoplasm (n = 256)
Total (n = 829)
234 (47%) 22 (4%)
7 (9%) 33 (43%)
125 (49%) 18 (7%)
366 (44%) 73 (9%)
149 (30%)
7 (9%)
16 (6%)
172 (21%)
91 (18%)
30 (39%)
97 (38%)
218 (26%)
whether blocks of tissue from the affected ovary were available, and if so by whether examination by the O T P confirmed that a neoplasm was present. There were 340 such cases in all, including 183 for which blocks of tissue were obtained. Neoplasms were found in 144 (78.7%) of the latter 183 cases. These 144 cases were added to the 685 cases initially ascertained from the O T R to give a total of 829 histologically confirmed subjects for the present study. The true number of cases missed because blocks of tissue were not obtained for them may be crudely estimated by assuming that the proportion of true cases was the same for the 157 cases for which tissue blocks were not available as for the other 183 n o n - O T R cases. In this case, ovarian neoplasms would have been present in 78.7% (124 of the 157). Adding this figure of 124 to the number of histologically confirmed cases (829) gives an estimate of 953 for what the size o f the series would have been if tissue blocks had been available for all cases. The 829 cases studied amount to 87% of this estimate. Corresponding estimates for the individual sources are given on the last three rows of Table I. These estimates suggest that a m o n g all the true cases of neoplasms identified from H A A and R C R respectively, 97% and 84% were included in the study. Given that all the 829 cases studied had been in hospital with ovarian neoplasms during the study period, all should have had an H A A record with a main or subsidiary diagnosis of primary ovarian neoplasm. Table I! shows that according to the O T P this was only true of just over half the 829 cases, regardless of whether the neoplasms were of benign, borderline or malignant behaviour; and it was only in a minority of cases - a small minority in the borderline group - that the H A A record was correct, not only as to the presence of a neoplasm but also as to its behaviour. A m o n g the cases in which primary ovarian neoplasms were not recorded in H A A , a majority of those with benign neoplasms and small minorities of borderline and malignant cases were described in H A A as having ovarian cysts or in a few cases other genito-urinary neoplasms. The remainder had no H A A record of hospital admission with these conditions either. Another way of looking at the quality of H A A data is to consider what proportions of the diagnoses of ovarian neoplasms in H A A records were correct according to the OTP. Table III shows that the O T P reviewed 461 cases with such a diagnosis. In 79% of these cases, the H A A record was correct as to both the presence and the behaviour of a neoplasm; in 16% it was correct as to presence but not behaviour; and in 5% the O T P found no neoplasm. These figures largely reflect the distributions of the cases with H A A
A. K. Mukherjee et al.
74 Table III
Accuracy of HAA reports of ovarian neoplasms
OTP diagnosis
Primary ovarian neoplasm: Behaviour as in HAA Behaviour not as in HAA No primary ovarian neoplasm
Number (% of n) by HAA diagnosis Benign neoplasm (n = 273)
Borderline neoplasm (n = 28)
Malignant neoplasm (n = 160)
Total (n=461)
234 (86%) 26 (10%) 13 (5%)
7 (25%) 20 (71%) 1 (4%)
125 (78%) 27 (17%) 8 (5%)
366 (79%) 73 (16%) 22 (5%)
diagnoses of benign and malignant neoplasms; only in a quarter of the cases diagnosed as borderline neoplasms according to H A A was the diagnosis correct as to behaviour. The completeness and accuracy of the R C R data are examined in Tables IV VI. These tables relate only to cases which had borderline or malignant neoplasms according to the O T P or the R C R , since benign ovarian neoplasms are not eligible for R C R registration. Table IV shows that the O T P diagnosed borderline neoplasms in 77 and malignant neoplasms in 256 of the 829 study cases, and that 42% o f the borderline and 23% of the malignant cases had not been registered with the R C R by the time the list of R C R registrations was obtained (which happened between 26 and 27 months after the end of the study period). The behaviour recorded by the R C R for the registered cases was consistent with that agreed by the OTP whenever the O T P rating was malignant but only in just over three quarters of cases when it was borderline. The proportions of R C R registrations in which behaviour was recorded correctly according to the O T P are shown in Table V. Forty cases were registered as borderline and 243 as malignant, and the recording of behaviour was correct according to the O T P in over 80% of each of these groups. All those incorrectly registered as borderline were classified as benign by the OTP. O f those incorrectly registered as malignant, the O T P classified a quarter as borderline, a quarter as benign, and a half as having no primary ovarian neoplasm. The cases registered as borderline or malignant by the R C R included 241 which were also rated borderline or malignant by the OTP. In Table VI, the reliability of the R C R ' s
Table IV Completeness of RCR registration of histologically confirmed registrable ovarian neoplasms Number (% of n) by OTP diagnosis RCR status
Registered as ovarian neoplasm: Behaviour correctly recorded Behaviour incorrectly recorded Not registered as ovarian neoplasm
Total
Borderline neoplasm (n = 77)
Malignant neoplasm (n = 256)
(n = 333)
34 (44%) 11 (14%) 32 (42%)
196 (77%) o (0%) 60 (23%)
230 (69%) II (3%) 92 (28%)
Health Authority and Cancer Registry Records
75
Table V Accuracy of cancer registry reports as to reality and behaviour of ovarian neoplasms OTP diagnosis
Registrable (borderline or malignant) neoplasm: Behaviour as in RCR Behaviour not as in RCR Non-registrable (benign) neoplasm No primary ovarian neoplasm
Number (% of n) by RCR diagnosis Borderline neoplasm (n = 40)
Malignant neoplasm (n = 243)
Total (n = 283)
34 (85%) 0 (0%) 6 (15%) 0 (0%)
196 (81%) 11 (5%) 11 (5%) 25 (10%)
230 (81%) 11 (4%) 17 (6%) 25 (9°./0)
histological data for these cases has been explored by classifying each case according to the tissues from which the RCR registration and the OTP assessment implied that it might have arisen. The 241 cases included 182 which were common 'epithelial' in origin according to the RCR - an assessment which was confirmed by the OTP in 97% of these cases. There was much less agreement about the remaining 59 cases: 59% of them (15% of all cases) fell into the RCR miscellaneous group but were classified as common 'epithelial' by the OTP, and the R C R record was also inconsistent with the OTP finding in a further 19% of the 59. Discussion
HAA and cancer registration records proved less complete sources o f diagnostic data in this study than might have been expected from previous work. Ovarian tissue from all the women in the study had been removed during the study period, implying that these women had undergone in-patient treatment then which should have generated HAA records for all 829 of them and R C R records for the 333 with borderline or malignant neoplasms. However, HAA records of ovarian cysts or neoplasms were only found for 74% of the 829 (Table II) and R C R records were only found for 72% of the 333 (Table IV). By contrast, H A A and R C R records were each found for more than 90% of cases eligible for cancer registration in an investigation in which methods comparable to those of the present study were used to study childhood neoplasms in the N o r t h Western Health Region in the early 1970s. 2 Studies in which three different methods were used to assess the completeness of cancer registration at all ages also suggest that during the 1970s the RCR's records were more than 90% complete. 1"3 None of these earlier studies yielded figures to compare with the OTP's finding that 15% of the cases that were entered as registrable primary ovarian neoplasms at the RCR, and 5% of those with diagnoses of ovarian neoplasms in HAA files, should not have been so recorded (Tables V and III). Among possible reasons for the H A A and R C R listings used in the present study being less complete than previous studies would lead one to expect, a deterioration in the completeness of H A A and RCR records seems a much less likely explanation than that some records which should have been printed out on these lists were omitted because they had been wrongly attributed to places of residence outside the study area or to dates of presentation outside the study period. Support for this view is provided by studies elsewhere in which the frequency o f errors was 8% for local authority area of residence and 0.6% for date of hospital admission in HAA records 7, and 2% for area of residence and
A.K. Mukherjee et al.
76
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