Capture-recapture method to determine the best design of a surveillance system. Application to a thyroid cancer registry

Estimating the number of people who inject drugs using repeated respondent-driven sampling (RDS) in a community-based program: implications for the burden of hepatitis C and HIV infections and harm reduction coverage

Estimates of the population size of people who inject drugs (PWID) are essential for efficient program planning and for monitoring key targets. Existing estimates in Greece are based on the capture-recapture method applied to drug treatment sources. We aimed to obtain estimates based on data collected from a community-based program addressing PWID in Athens, Greece. The program was implemented in 2012-2013 to increase diagnosis and treatment for HIV among PWID during an HIV outbreak. Five Responden-Driven Sampling (RDS) rounds were used to recruit participants. A unique code was used to identify participants among rounds. Capture-recapture was applied to estimate the population size in 2013 (PWID with injection in the past 12 months; active PWID with injection in the past 30 days). Log-linear models were applied. In 2013, the estimated number of active PWID in Athens was 4,117 [95% confidence interval (CI): 3,728-4,507] (vs. 1,956 [95% CI: 1,525-2,565] the existing population size estimate). Based on this estimate, the coverage of needle and syringe programs in 2013 was 103 syringes/PWID/year (vs. 216 based on the existing estimate). The population prevalence of injecting drug use in Athens (past 12 months) was 0.222% (95% CI: 0.200-0.245). The inclusion of data from community-based programs in the estimation of the PWID population size resulted in 2.1-fold higher estimates, compared to the official estimates obtained from drug treatment data, and indicates the need for re-evaluation of necessary resources for harm reduction and elimination of HIV and hepatitis C in PWID.

Estimation of the incidence of invasive meningococcal disease using a capture-recapture model based on two independent surveillance systems in Catalonia, Spain

OBJECTIVES

Invasive meningococcal disease (IMD) is an urgent notifiable disease and its early notification is essential to prevent cases. The objective of the study was to assess the sensitivity of two independent surveillance systems and to estimate the incidence of IMD.

DESIGN

We used capture-recapture model based on two independent surveillance systems, the statutory disease reporting (SDR) system and the microbiological reporting system (MRS) of the Public Health Agency of Catalonia, between 2011 and 2015. The capture-recapture analysis and 95% CIs were calculated using the Chapman formula. Multivariate vector generalised linear model was performed for adjusted estimation.

MEASURES

The variables collected were age, sex, year of report, size of municipality (<10 000 and ≥10 000), clinical form, death, serogroup, country of birth and type of reporting centre (private and public).

RESULTS

The sensitivity of the two combined surveillance systems was 88.5% (85.0-92.0). SDR had greater sensitivity than the MRS (67.9%; 62.7-73.1 vs 64.7%; 59.4-70.0). In 2014-2015, the sensitivity of both systems was higher (80.6%; 73.2-87.9 vs 73.4%; 65.2-81.6) than in 2011-2013 (59.3%; 52.6-66.0 vs 58.3%; 51.6-65.1). In private centres, the sensitivity was higher for SDR than for MRS (100%; 100-100 vs 4.8%; -4.4-13.9). The adjusted estimate of IMD cases was lower than that obtained using the Chapman formula (279; 266-296 vs 313; 295-330). The estimated adjusted incidence of IMD was 0.7/100 000 persons-year.

CONCLUSIONS

The sensitivity of enhanced surveillance through the combination of two complementary sources was higher than for the sources individually. Factors associated with under-reporting in different systems should be analysed to improve IMD surveillance.

Estimating the number of farms experienced foot and mouth disease outbreaks using capture-recapture methods

Foot and mouth disease (FMD) is recognized as an endemic disease in Thailand and throughout other countries in Southeast Asia. The underreporting of FMD outbreaks has affected the true status of the disease. This study aimed to determine the number of dairy farms in Chiang Mai that had experienced FMD outbreaks (FMD outbreak farm) during 2015-2016 using capture-recapture (CR) methods. Two independent FMD outbreak data sources including data from the livestock authorities and survey questionnaires were analyzed using Chapman estimator and Chao estimator. Results showed that the estimated number of FMD outbreak farms was 264 (95% CI = 250, 277) and 273 (95% CI = 259, 292) farms based on the Chapman estimator and Chao estimator, respectively. The estimated prevalence of FMD corresponding to the Chapman estimator was lower than the Chao estimator. The active approach of the survey method offered a higher degree of sensitivity compared to the passive method used by the livestock authorities. Estimations from the CR method provided an upper bound for the true number of outbreak farms. This study demonstrated the use of the CR method to estimate the true status of FMD outbreaks. Our proposed approach can potentially be used as a tool to enhance the accuracy and sensitivity of established monitoring and surveillance systems.

Hepatitis A surveillance: sensitivity of two information sources

BACKGROUND

The frequency of mild forms of hepatitis A, especially in children, could lead to underreporting. The objective of the study was to investigate the sensitivity of two surveillance systems, mandatory Statutory Disease Reports and the Microbiological Reporting System of Catalonia, using capture-recapture techniques.

METHODS

The study was conducted in Catalonia between 2011 and 2015. Hepatitis A cases reported to two independent surveillance systems were included: Statutory Disease Reports (SDR) and Microbiological Reporting System of Catalonia (MRS). The variables collected were: age, sex, year of declaration, size of municipality (< 10,000 and ≥ 10,000), country of birth (Spain or abroad), reporting centre (primary care/hospital) and notification method (electronic or paper). The capture-recapture analysis and the estimate of 95% confidence intervals were made using the Chapman formula for comparison of two sources, both for the estimate of the total number of cases and the stratification according to variables. Multinomial logistic regression was performed to obtain an adjusted estimate.

RESULTS

The SDR had a greater overall sensitivity than the MRS (48.8%; 43.5-55.6 vs. 19.3%; 17.2-21.9). In cases aged < 15 years the sensitivity of both systems was higher (76.6%; 72.7-81 vs. 25.2%; 20.9-29.5) than in cases aged > 15 years (25.5%; 22.8-28.3 vs. 12.1%; 10-14.2). For those born in Spain, the sensitivity was 57.2% (49.6-67.4) in the SDR and 27.1% (23.5-31.9) in the MRS, lower than that for foreign-born patients (58%; 51.2-66.8 vs. 49.1%; 43.4-56.6). In electronically-reported cases, the sensitivity was much higher in the SDR than in the MRS (47.2%; 42.3-52.1 vs. 9.4%; 6.5-12.3). No differences were observed according to sex, size of municipality, and year of declaration or reporting centre. The estimated total number of cases using the Chapman formula was very similar to the adjusted estimate (1121; 985-1258 vs. 1120; 876-1525), indicating the robustness of the results.

CONCLUSIONS

The sensitivity of the SDR was greater than that of MRS, especially in patients aged < 15 years, although for patients born abroad the difference in sensitivity was lower. Reinforced surveillance combining the SDR and MRS improves the efficiency in the detection of cases.

Bayesian estimation of a cancer population by capture-recapture with individual capture heterogeneity and small sample

BACKGROUND

Cancer incidence and prevalence estimates are necessary to inform health policy, to predict public health impact and to identify etiological factors. Registers have been used to estimate the number of cancer cases. To be reliable and useful, cancer registry data should be complete. Capture-recapture is a method for estimating the number of cases missed, originally developed in ecology to estimate the size of animal populations. Capture recapture methods in cancer epidemiology involve modelling the overlap between lists of individuals using log-linear models. These models rely on assumption of independence of sources and equal catchability between individuals, unlikely to be satisfied in cancer population as severe cases are more likely to be captured than simple cases.

METHODS

To estimate cancer population and completeness of cancer registry, we applied M(th) models that rely on parameters that influence capture as time of capture (t) and individual heterogeneity (h) and compared results to the ones obtained with classical log-linear models and sample coverage approach. For three sources collecting breast and colorectal cancer cases (Histopathological cancer registry, hospital Multidisciplinary Team Meetings, and cancer screening programmes), individual heterogeneity is suspected in cancer population due to age, gender, screening history or presence of metastases. Individual heterogeneity is hardly analysed as classical log-linear models usually pool it with between-"list" dependence. We applied Bayesian Model Averaging which can be applied with small sample without asymptotic assumption, contrary to the maximum likelihood estimate procedure.

RESULTS

Cancer population estimates were based on the results of the M(h) model, with an averaged estimate of 803 cases of breast cancer and 521 cases of colorectal cancer. In the log-linear model, estimates were of 791 cases of breast cancer and 527 cases of colorectal cancer according to the retained models (729 and 481 histological cases, respectively).

CONCLUSIONS

We applied M(th) models and Bayesian population estimation to small sample of a cancer population. Advantage of M(th) models applied to cancer datasets, is the ability to explore individual factors associated with capture heterogeneity, as equal capture probability assumption is unlikely. M(th) models and Bayesian population estimation are well-suited for capture-recapture in a heterogeneous cancer population.

Estimation of cancer cases using capture-recapture method in Northwest Iran

BACKGROUND

Under-ascertainment and over-ascertainment are common phenomena in surveillance and registry systems of health-related events. Capture-recapture is one of the methods which is applied to determine the sensitivity of surveillance or registry systems to recognize cancer cases. This study aimed to estimate the number of cancers using data available both in the Cancer Registry Center of Northwestern Iran and in the Population-based Cancer Registry Center of Iran.

MATERIAL AND METHODS

The studied population consisted of all cancerous cases in the northwest of Iran from 2008 to 2010. All data were extracted from two resources and entered into Microsoft Excel software. After removing common and repeat cases the data were statistically analyzed using a capture-recapture studies' specific software "CARE 1.4". Estimations were calculated by Chapman and Petersen methods with the approximate confidence interval of 95%.

RESULTS

From 2008 to 2010, the number of all cancer cases was estimated to be 21,652 (CI 95%: 19,863-22,101). Sensitivity rate of all cancer cases was 83.9% and that of Population-based Cancer Registry Center of Iran was 52%. It was 93.1% considering both resources.

CONCLUSION

Using two resources and the capture-recapture method rather than a single resource may be a more reliable method to estimate the number of cancer cases.

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.

A comparison of two surveillance strategies for selected birth defects in Florida

OBJECTIVE

We linked data from two independent birth defects surveillance systems with different case-finding methods in an overlapping geographic area to assess Florida's suveillance of birth defects (e.g., neural tube defects, orofacial clefts, gastroschisis/omphalocele, and chromosomal defects), focusing on sensitivity and completeness of ascertainment measures.

METHODS

Live-born infants identified from each system born during 2003-2006 in a nine-county catchment area with specific birth defects were linked to birth certificates. Using the enhanced surveillance system as a gold standard, we calculated the sensitivity of the Florida Birth Defects Registry (FBDR) for identifying infants. Next, we used capture-recapture models to estimate the completeness of case ascertainment and the prevalence of each birth defect in the catchment area. We used multivariable logistic regression models with backward elimination to estimate adjusted odds ratios and 95% confidence intervals for factors significantly associated with the FBDR's failure to capture infants ultimately identified by enhanced surveillance.

RESULTS

The FBDR's sensitivity was 89.3%, and the overall completeness of ascertainment was estimated as 86.6%. Defect-specific sensitivity and completeness of ascertainment varied significantly by defect. The combined defect-specific sensitivity for all malformations under study was 86.6%; completeness of ascertainment ranged from 45.6% for anencephaly to 88.6% for Down syndrome, 87.9% for spina bifida without anencephaly, and 87.0% for orofacial clefts.

CONCLUSIONS

For the defects under study, the FBDR captured nearly nine of every 10 infants born with selected birth defects. However, the FBDR's ability to identify specific defects was both more limited and defect dependent with widely varying defect-specific sensitivities.

Investigating the completeness of a histopathological cancer registry: estimation by capture-recapture analysis in a French geographical unit Alpes-Maritimes, 2008

INTRODUCTION

Cancer population studies require reliable and complete baseline data, which should theoretically be available by collecting histopathology records. The completeness of such a collection was evaluated using capture-recapture analysis based on three data sources concerning breast and colorectal cancers over an identical period and within the same geographical area.

METHOD

The total number of breast and colon cancer cases was estimated using capture-recapture analysis based on the number of cases which were common or not between sources recording screened, diagnosed and treated cancers in the French Alpes Maritimes district.

RESULT

The estimated total number of new cases of breast cancer diagnosed among Alpes Maritimes residents women aged 50-75 was 791 (95% CI: 784-797) in 2008. Of these 791 cases, 729 were identified through histopathology records, thus amounting to 92.2% completeness (95% CI: 91.5-93.0%). The total estimated number of new cases of colorectal cancer diagnosed among Alpes Maritimes residents aged 50-75 was 527 (95% CI: 517-536). Of these 527 cases, 481 were identified through histopathology records, thus amounting to 91.3% completeness (95% CI: 89.7-93.0%).

CONCLUSION

The estimated completeness of cancer records collected from histopathology laboratories was higher than 90% for new cases of breast and colorectal cancer within the age range concerned by the screening programme. A verified and validated histopathology data collection may be useful for cancer population studies.

Time trends and geographic variations for thyroid cancer in New Caledonia, a very high incidence area (1985-1999)

Thyroid cancer incidence in New Caledonia is the highest reported in the world and is approximately 10-fold higher than in most developed countries. We describe the incidence patterns in this country according to histological and sociodemographic characteristics to give clues about potential etiologic factors. Another objective is to see whether the incidence figures are related to enhanced detection of small size carcinomas. The study included all 498 cases of thyroid cancer diagnosed in 1985-1999. Pathology reports were systematically reviewed to determine the histological type of the tumor and the size of the cancerous nodules. The incidence of carcinomas < or =10 mm was taken as an indicator of enhanced detection due to improved screening procedures. The age-standardized incidence rates in 1985-1999 were exceptionally high in Melanesian women (71.4/100,000) and men (10.4/100,000). The incidence increased three-fold in women from 1995 onwards. The increase in incidence was more striking for papillary carcinomas < or =10 mm than for large size carcinomas, but an increased incidence of carcinomas >10 mm was also observed among women. The analysis by municipality of residence in Melanesian women showed that the incidence was twice as high in 1995-1999 in the Loyalty Islands as in the rest of the country. The sharp increase of thyroid cancer incidence in 1985-1999 in New Caledonia was partly related to enhanced detection of small size carcinomas. The elevated incidence of thyroid cancers, as well as the ethnic and geographic disparities, may result from common environmental or lifestyle risk factors that need to be identified.

[Role of hospital claims databases from care units for estimating thyroid cancer incidence in the Rhône-Alpes region of France]

BACKGROUND

Incidence measures are essentially based on the data collected by cancer registries. Hospital claims databases from care units (PMSI) can be used as a source of information for registries because they contain standard records of most cancer patients. Regarding thyroid cancer, we have evaluated the PMSI as a source of information for the Rhône-Alpes thyroid cancer registry and usefulness of PMSI as a tool for surveillance of thyroid cancer incidence.

METHODS

Patients with incident thyroid cancer in 2002 were identified in the claims data of the Rhône-Alpes region using an algorithm based on DRG codes of thyroidectomy and on diagnosis codes of thyroid cancer in a principal or secondary position. The patients identified were compared to those in thyroid cancer registry of the Rhône-Alpes region regarding sex, age, ZIP code of residence, month of discharge and length of stay versus the diagnosis date. When the percentage of cases of claims data identified in the cancer registry and the percentage of cases of the cancer registry identified in claims data were obtained, the capture-recapture method was applied to estimate the number of missing cases and the total number of incident thyroid cancers in the region.

RESULTS

667 patients were identified in claims data while the cancer registry included 677 patients. 95.2% of patients identified in claims data were in the cancer registry and 82.3% of patients in the cancer registry were identified in claims data. Cases lacking in claims data mostly corresponded to micro-cancers which represented 41% of cases in the cancer registry. Regarding cancer above 1 cm, 92% of the cancer registry cases were identified in claims data. Sensitivity of combining information from cancer registry and claims data was 99.2%. Cases lacking in cancer registry, present in claims data base and considered as true cases after obtaining pathological confirmation represented 2% of the whole thyroid cancer population.

CONCLUSION

Claims data obtained from anonymous regional or national bases can be helpful for checking the completeness of thyroid cancer registries and to provide a small amount of unknown cases. They can be considered an acceptable tool for surveillance of thyroid cancer incidence. The significance of the variations in incidence that could be observed from claims data remains to be evaluated in comparison with comparable data obtained from registries.

Problems in using birth certificate files in the capture-recapture model to estimate the completeness of case ascertainment in a population-based birth defects registry in New York State

BACKGROUND

The limitations and underlying assumptions of the capture-recapture methods have hindered their application in epidemiological settings, especially in evaluating the completeness of birth defects registries. This study explored the possibility of using birth certificates as the secondary data source in a simple two-source capture-recapture model to estimate the completeness of case ascertainment of the Congenital Malformations Registry (CMR) for selected major birth defects.

METHODS

The CMR and the birth certificates were used as the primary and secondary sources, respectively. Children who were born in 1996-2001 and had selected major birth defects were identified from the two sources. The accuracy of the diagnoses was examined by comparing the individual birth defect categories of the children from the two sources.

RESULTS

Discrepancies in birth defect categories in the two data sources and false positives in the birth certificates were the major problems encountered in estimating the completeness of the CMR using the simple two-source capture-recapture method. The estimated completeness for selected major birth defects was only about 71%. Stratified analyses resulted in relatively high estimated completeness for oral clefts (90%) and Down syndrome (88%). CONCLUSIONS Although the birth certificate data was not a good source for estimating the completeness of case ascertainment of the CMR using capture-recapture methods, the analyses provided reasonable estimates for some conditions that were relatively easy to identify and diagnose at birth, such as oral clefts and Down syndrome.

Using Medicare Data to Estimate the Number of Cases Missed by a Cancer Registry

BACKGROUND

Cancer surveillance is essential for assessing patterns of cancer occurrence. State cancer registries do not capture all available cases potentially biasing results. Secondary data may be useful in identifying new cases and estimating the number of cases missed.

OBJECTIVE

We sought to create 2 distinct data sources from Medicare claims to use in combination with registry data as 3 sources for a capture-recapture analysis to estimate the capture rate and bias in capture of a statewide cancer registry.

METHODS

Data from the Virginia cancer registry (Registry) were merged with Medicare inpatient (Part A) as well as Medicare outpatient and physician claims (Part B) to provide 3 sources to estimate missing cases. A 3-source loglinear model was used to estimate the number of missing cancer cases for breast, lung, colorectal, and prostate cancer. Models included main effects and interactions. Additional analysis looked at the effect of demographic and comorbidity variables.

RESULTS

Loglinear models demonstrated mostly positive dependence between the 3 sources, implying that 2-source models would underestimate missing cases and overestimate capture rates. Using capture-recapture estimates of total number of cancer cases as the denominator, capture rates for Registry ranged from 59% (colorectal) to 74% (lung). When the aggregate of cases found by either Medicare or Registry were used the capture rates ranged from 74% (prostate) to 89% (breast). Further analysis indicated that capture rates differed by demographic characteristics.

CONCLUSION

We conclude that Medicare claims are useful to supplement a Registry, estimate the number of missing cases, and assess bias in capture.