Cancer occurrence in the elderly: agreement between three major data sources

A practical framework for data management processes and their evaluation in population-based medical registries

INTRODUCTION

We present a framework for data management processes in population-based medical registries. Existing guidelines lack the concreteness we deem necessary for them to be of practical use, especially concerning the establishment of new registries. Therefore, we propose adjustments and concretisations with regard to data quality, data privacy, data security and registry purposes.

MATERIALS AND METHODS

First, we separately elaborate on the issues to be included into the framework and present proposals for their improvements. Thereafter, we provide a framework for medical registries based on quasi-standard-operation procedures.

RESULTS

The main result is a concise and scientifically based framework that tries to be both broad and concrete. Within that framework, we distinguish between data acquisition, data storage and data presentation as sub-headings. We use the framework to categorise and evaluate the data management processes of a German cancer registry.

DISCUSSION

The standardisation of data management processes in medical registries is important to guarantee high quality of the registered data, to enhance the realisation of purposes, to increase efficiency and to enable comparisons between registries. Our framework is destined to show how one central impediment for such standardisations - lack of practicality - can be addressed on scientific grounds.

Agreement of diagnosis and its date for hematologic malignancies and solid tumors between medicare claims and cancer registry data

PURPOSE

Claims data may be a suitable source studying associations between drugs and cancer. However, linkage between cancer registry and claims data including pharmacy-dispensing information is not always available. We examined the accuracy of claims-based definitions of incident cancers and their date of diagnosis.

METHODS

Four claims-based definitions were developed to identify incident leukemia, lymphoma, lung, colorectal, stomach, and breast cancer. We identified a cohort of subjects aged >or=65 (1997-2000) from Pennsylvania Medicare and drug benefit program data linked with the state cancer registry. We calculated sensitivity, specificity, and positive predictive values of the claims-based definitions using registry as the gold standard. We further assessed the agreement between diagnosis dates from two data sources.

RESULTS

All definitions had very high specificity (>or=98%), while sensitivity varied between 40% and 90%. Test characteristics did not vary systematically by age groups. The date of first diagnosis according to Medicare data tended to be later than the date recorded in the registry data except for breast cancer. The differences in dates of first diagnosis were within 14 days for 75% to 88% of the cases. Bias due to outcome misclassification of our claims-based definition of cancer was minimal in our example of a cohort study.

CONCLUSIONS

Claims data can identify incident hematologic malignancies and solid tumors with very high specificity with sufficient agreement in the date of first diagnosis. The impact of bias due to outcome misclassification and thus the usefulness of claims-based cancer definitions as cancer outcome markers in etiologic studies need to be assessed for each study setting.

In the absence of cancer registry data, is it sensible to assess incidence using hospital separation records?

BACKGROUND

Within the health literature, a major goal is to understand distribution of service utilisation by social location. Given equivalent access, differential incidence leads to an expectation of differential service utilisation. Cancer incidence is differentially distributed with respect to socioeconomic status. However, not all jurisdictions have incidence registries, and not all registries allow linkage with utilisation records. The British Columbia Linked Health Data resource allows such linkage. Consequently, we examine whether, in the absence of registry data, first hospitalisation can act as a proxy measure for incidence, and therefore as a measure of need for service.

METHODS

Data are drawn from the British Columbia Linked Health Data resource, and represent 100% of Vancouver Island Health Authority cancer registry and hospital records, 1990-1999. Hospital separations (discharges) with principal diagnosis ICD-9 codes 140-208 are included, as are registry records with ICDO-2 codes C00-C97. Non-melanoma skin cancer (173/C44) is excluded. Lung, colorectal, female breast, and prostate cancers are examined separately. We compare registry and hospital annual counts and age-sex distributions, and whether the same individuals are represented in both datasets. Sensitivity, specificity and predictive values are calculated, as is the kappa statistic for agreement. The registry is designated the gold standard.

RESULTS

For all cancers combined, first hospitalisation counts consistently overestimate registry incidence counts. From 1995-1999, there is no significant difference between registry and hospital counts for lung and colorectal cancer (p = 0.42 and p = 0.56, respectively). Age-sex distribution does not differ for colorectal cancer. Ten-year period sensitivity ranges from 73.0% for prostate cancer to 84.2% for colorectal cancer; ten-year positive predictive values range from 89.5% for female breast cancer to 79.35% for prostate cancer. Kappa values are consistently high.

CONCLUSION

Claims and registry databases overlap with an appreciable proportion of the same individuals. First hospital separation may be considered a proxy for incidence with reference to colorectal cancer since 1995. However, to examine equity across cancer health services utilisation, it is optimal to have access to both hospital and registry files.

The added value of claims for cancer surveillance: results of varying case definitions

OBJECTIVE

As cancer diagnosis and treatment has moved to the outpatient healthcare setting, traditional cancer surveillance tools are less effective for complete and unbiased capture of incident cases. This study evaluates the potential for Medicare data to supplement cancer surveillance in a unique manner by using a standard that is independent of a central cancer registry.

DESIGN

State cancer registry records were matched with Medicare data. Case validation included inpatient record abstraction combined with a mail/telephone survey of treating physicians. The positive predictive value (PPV), sensitivity (capture rate), and potential additional cases were calculated for 6 Medicare claims-based case definitions.

RESULTS

The PPV varied according to cancer site and definition, ranging from 70%-97% (prostate) to 87%-98% (breast). Sensitivity varied inversely with PPV, ranging from 51%-94% (breast) to 10%-88% (lung). The most important factors that predicted being missed by the registry were having no admission to an ACOS-certified hospital and no surgical treatment.

CONCLUSION

Medicare data represent a valid resource for supplementing state cancer registries in surveillance efforts. This potential is especially applicable to cancers predominantly diagnosed and treated outside the hospital setting.