Extracting Systemic Anticancer Treatment Lines from the Danish National Patient Registry for Solid Tumour Patients Treated in the North Denmark Region Between 2009 and 2019

Background

Reconstructing patient treatment trajectories is important to generate real-world evidence for epidemiological studies. The Danish National Patient Registry (DNPR) contains information about drug prescriptions and could therefore be used to reconstruct treatment trajectories. We aimed to evaluate and enhance two existing methods to reconstruct systemic anticancer treatment trajectories.

Methods

This study was based on data from 8738 consecutive patients with solid tumors treated in the North Denmark Region between 2009 and 2019. Two approaches found in the literature as well as two new approaches were applied to the DNPR data. All methods relied on time intervals between two consecutive drug administrations to determine if they belonged to the same treatment line. MedOnc, a local dataset from the Department of Oncology, Aalborg University Hospital was used as a reference. To evaluate the performance of each method, F1-scores were calculated after matching the lines identified in both datasets. We used three different matching strategies: stringent matching, loose matching, and matching based on line numbers, controlling for overfitting.

Results

Overall, the two new approaches outperformed the simpler and best performing of the two existing methods, with F1-scores of 0.47 and 0.45 vs 0.44 for stringent matching and 0.84 and 0.83 vs 0.82 for loose matching. Nevertheless, only one of the new methods outperformed the existing simpler method when matching on the number of lines (0.73 vs 0.72). Large differences were seen by cancer site, especially for the stringent and line number matchings. Performances were relatively stable by calendar year.

Conclusion

The high F1-scores for the new methods confirm that they should be generally preferred to reconstruct systemic anticancer treatment trajectories using the DNPR.

The positive predictive value of spontaneous subarachnoid hemorrhage diagnoses in the Danish National Patient Register

Introduction: Spontaneous (non-traumatic) subarachnoid hemorrhage (ntSAH) is frequently suspected in the emergency department, but the incidence rate is low. Diagnosis registers can provide valuable data for research in uncommon conditions like ntSAH. Unfortunately, validity vary in the registers. We aimed to assess the validity of the ntSAH diagnosis in the Danish National Patient Register (DNPR) and secondly to describe patients misclassified as ntSAH and to calculate the incidence rate of ntSAH. Methods: From the DNPR we extracted information on patients at least 18 years of age on admission registered with a diagnosis of ntSAH and admitted to a hospital in the Capital Region of Denmark between January 1, 2008 and December 31, 2014. Two independent investigators reviewed the medical records to assess if the diagnosis could be confirmed. Those not confirmed were categorized according to a predeveloped case report form. Results: We identified 1101 patients with a diagnosis of ntSAH; medical records were accessible for 1069 (97.7%) and 842 (78.8%) met the inclusion criteria. The diagnosis was confirmed in 537 patients (63.8% (95% confidence interval: 60.5-67.0%)). Among patients where ntSAH was not confirmed, 122 (40.0%) had a traumatic subarachnoid hemorrhage (tSAH), ntSAH had been suspected in 57 (18.9%) patients but was not substantiated during admission, while parenchymal hemorrhages were identified in 45 (14.5%) patients. The incidence rate was 5.5 (95% CI: 4.9-6.1) per 100,000 persons per year. Conclusion: We found a positive predictive value (PPV) of 63.8% for the diagnosis of non-traumatic subarachnoid hemorrhage in the Danish National Patient Register. The low PPV suggests that care should be taken if unvalidated data are used for research and that results of previous studies should be interpreted with caution.

Long-term benefits and risks of parathyroid hormone treatment in compliant osteoporotic patients. A Danish national register based cohort study

PURPOSE

Medical treatment of osteoporosis should preferably be both effective and have minimal side effects. The aim of the present study was to examine long-term benefits and risks of parathyroid hormone (PTH) treatment in compliant patients.

METHODS

This is a nationwide retrospective cohort study based on national registers in which we identified 1739 patients treated with PTH (2003-2010) (index cases) for at least 18 months and with a medication possession rate of > 0.8. For comparison, patients treated with bisphosphonate (BP) (n = 13,131) and anti-osteoporotic treatment-naïve controls (n = 12,721) were selected. Incidence of fractures, drug consumption, and comorbidity were compared between the three cohorts. Mean follow-up of the PTH-treated patients was 4.3 years (range 1.8-8.7 years).

RESULTS

Before initiation of treatment, PTH patients had a significantly higher Charlson comorbidity index score and more osteoporotic fractures than both BP patients and controls. No difference was detected in the incidence of fractures during PTH treatment or years after between PTH patients and BP patients. No significant difference in the use of drugs was seen between PTH and BP patients, except for PPI intake which was higher in PTH patients. No significant increases were found in the incidence of cancers or other ICD-10 diagnoses among PTH-treated patients in comparison with both BP and controls.

CONCLUSION

Overall, PTH treatment is effective and safe. Following PTH treatment in compliant patients, neither fracture incidence nor drug consumption differed between PTH-treated and BP-treated patients, despite the fact that PTH-treated patients had more severe osteoporosis. No increased incidence of malignant diseases or other diseases was detected.

Diagnosing gestational diabetes mellitus in the Danish National Birth Cohort

INTRODUCTION

The Danish National Birth Cohort (DNBC) contains comprehensive information on diet, lifestyle, constitutional and other major characteristics of women during pregnancy. It provides a unique source for studies on health consequences of gestational diabetes mellitus. Our aim was to identify and validate the gestational diabetes mellitus cases in the cohort.

MATERIAL AND METHODS

We extracted clinical information from hospital records for 1609 pregnancies included in the Danish National Birth Cohort with a diagnosis of diabetes during or before pregnancy registered in the Danish National Patient Register and/or from a Danish National Birth Cohort interview during pregnancy. We further validated the diagnosis of gestational diabetes mellitus in 2126 randomly selected pregnancies from the entire Danish National Birth Cohort. From the individual hospital records, an expert panel evaluated gestational diabetes mellitus status based on results from oral glucose tolerance tests, fasting blood glucose and Hb1c values, as well as diagnoses made by local obstetricians.

RESULTS

The audit categorized 783 pregnancies as gestational diabetes mellitus, corresponding to 0.89% of the 87 792 pregnancies for which a pregnancy interview for self-reported diabetes in pregnancy was available. From the randomly selected group the combined information from register and interviews could correctly identify 96% (95% CI 80-99.9%) of all cases in the entire Danish National Birth Cohort population. Positive predictive value, however, was only 59% (56-61%).

CONCLUSIONS

The combined use of data from register and interview provided a high sensitivity for gestational diabetes mellitus diagnosis. The low positive predictive value, however, suggests that systematic validation by hospital record review is essential not to underestimate the health consequences of gestational diabetes mellitus in future studies.

Positive predictive values of the International Classification of Diseases, 10th revision diagnoses of Gram-negative septicemia/sepsis and urosepsis for presence of Gram-negative bacteremia

Background

Health care databases are a valuable resource for infectious disease epidemiology if diagnoses are accurately coded. We examined the ability of diagnostic coding to accurately identify Gram-negative bacteremia.

Methods

We randomly selected 100 patients among 1,703 patients recorded in the Danish National Patient Register with a diagnosis of either “septicemia/sepsis due to other Gram-negative organisms” (International Classification of Diseases, 10th revision [ICD-10] code A41.5) or “urosepsis” (ICD-10 code A41.9B) who had been admitted at Aalborg University Hospital, Denmark between 1994 and 2012. We estimated the positive predictive value (PPV) of these diagnoses for presence of Gram-negative bacteremia, using microbiological results from blood cultures as standard reference. Complementary clinical information was obtained from the medical records.

Results

Of the 100 patients registered with Gram-negative septicemia/sepsis or urosepsis, 72 had blood culture confirmed Gram-negative bacteremia, four patients had monomicrobial Gram-positive bacteremia, 21 patients had a negative blood culture, and three had no blood culture taken. The overall PPV of a blood culture confirmed Gram-negative bacteremia diagnosis was 72% (95% confidence interval [CI]: 62%–81%); for ICD-10 code A41.5 it was 86% (95% CI: 74%–94%) and for ICD-10 code A41.9B it was 55% (95% CI: 39%–70%). The highest PPV was achieved for diagnoses registered in the most recent calendar period (2009–2012) and for secondary discharge diagnoses.

Conclusion

Our findings indicated good agreement between ICD-10 code A41.5 “septicemia/sepsis due to other Gram-negative organisms” and Gram-negative bacteremia, whereas ICD-10 code A41.9B “urosepsis” was not suited for identification of Gram-negative bacteremia.

Risk of cancer in patients with inflammatory bowel diseases: a nationwide population-based cohort study with 30 years of follow-up evaluation

BACKGROUND & AIMS

Data regarding the risk of gastrointestinal and extraintestinal cancers in Crohn's disease (CD) and ulcerative colitis (UC) are needed to understand the clinical course of inflammatory bowel diseases (IBDs) and their treatments.

METHODS

We performed a nationwide historical cohort study using Danish health care databases. We identified patients with a diagnosis of CD or UC, recorded from 1978 through 2010, and followed them up until the first occurrence of cancer, death, or emigration. We used standardized incidence ratios (SIRs) to compare cancer incidence in CD and UC patients with that expected in the general population.

RESULTS

Excluding cancers diagnosed within 1 year of IBD diagnosis, 772 cases of invasive cancer occurred among 13,756 patients with CD (SIR, 1.3; 95% confidence interval [CI], 1.2-1.4) and 2331 occurred among 35,152 patients with UC (SIR, 1.1; 95% CI, 1.0-1.1). CD was associated weakly with gastrointestinal cancers (SIR, 1.2; 95% CI, 1.0-1.4) and extraintestinal cancers (SIR, 1.3; 95% CI, 1.2-1.4), with the strongest associations for hematologic malignancies (SIR, 1.9; 95% CI, 1.5-2.3), smoking-related cancers (SIR, 1.5; 95% CI, 1.3-1.8), and melanoma (SIR, 1.4; 95% CI, 1.0-1.9). Associations between UC and gastrointestinal and extraintestinal cancers were weaker (SIR, 1.1; 95% CI, 1.0-1.2; and SIR, 1.1; 95% CI, 1.0-1.1, respectively). The relative risk of extraintestinal cancers among patients with IBD was relatively stable over time, although the risk of gastrointestinal cancers decreased.

CONCLUSIONS

Patients with IBD, particularly CD, are at increased risk for gastrointestinal and extraintestinal malignancies. The relative risk of gastrointestinal malignancy has decreased since 1978, without a concomitant increase in the risk of nongastrointestinal malignancy.

Positive predictive value of the diagnosis coding for vitamin B12 deficiency anemia in the Danish National Patient Register

PURPOSE

The aim of this validation study was to assess the positive predictive value (PPV) of the International Classification of Diseases, 10th revision (ICD-10) diagnosis of vitamin B12 (cobalamin [Cbl]) deficiency anemia in the Danish National Patient Register (DNPR).

PATIENTS AND METHODS

We identified all patients above 18 years of age recorded in the DNPR with a diagnosis of Cbl deficiency anemia (ICD-10 code: D51) admitted to two Danish university hospitals and one Danish regional hospital from 2000 through 2009. We assessed the PPV using biochemical parameters on Cbl deficiency with or without anemia as reference standards. These data were obtained from the Laboratory Information Systems Database. Data on prescriptions with Cbl supplementation drugs were obtained from the Aarhus University Prescription Database.

RESULTS

We identified 1089 patients coded with a Cbl deficiency anemia diagnosis in the DNPR. The PPV was 31.5% (95% confidence interval [CI]: 28.8%-34.3%) and 36.8% (95% CI: 34.0%-39.7%) depending on definitions of Cbl deficiency with anemia. When using Cbl deficiency without anemia as a reference standard, the PPV was 51.3% (95% CI: 48.4%-54.3%). The PPV for Cbl supplemented patients was 22.2% (95% CI: 18.0%-26.9%) and for non-Cbl supplemented patients 63.9% (95% CI: 60.5%-67.3%).

CONCLUSION

The PPVs of the ICD-10 diagnosis coding for Cbl deficiency anemia were generally low in the DNPR. Therefore, this register should be used with caution to study patients with Cbl deficiency anemia.