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Introduction: National discharge registers are important and cost-effective data sources for administrative and research purposes, but their value depends much on the validity of the registered data. The objective of this study was to assess the validity of heart failure (HF) diagnoses (ICD10: I50.0-I50.9) in the Danish National Patient Register (DNPR)., Methods: We reviewed medical records from a random sample of 500 patients with either a primary or a secondary discharge diagnosis of HF registered in the DNPR from any department in Northern Denmark in 2007. We noted symptoms, objective signs, diagnostic imaging and biomarkers and used the European Society of Cardiology definition of HF to categorise patients into definite, probable or non-
verified HF., Results: We classified 305 patients as having definite HF and 113 patients as having probable HF. The remaining cases were classified as non-verified HF. Thus, the positive predictive value (PPV) for definite and probable HF was 83.6% (95% confidence interval (CI): 80.1-86.7%).
The PPV increased to 88.0% (95% CI: 84.4-91.0%) when we restricted analyses to primary diagnoses and to 95.2% (95% CI: 89.2-98.4%) when we restricted analyses to HF diagnoses established at cardiology units., Conclusions: The HF diagnoses (I50.0-I50.9) in the DNPR should be used with caution if validation is not possible. However, restricting analyses to patients registered with a primary diagnosis of HF or patients discharged from cardiology units may be a useful alternative in population-based studies., Funding: none., Trial Registration: not relevant., (Articles published in the DMJ are “open access”. This means that the articles are distributed under the terms of the Creative Commons Attribution Non-commercial License, which permits any non-commercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.)

Aims: To examine temporal changes in incidence and 1-year mortality of first myocardial infarction (MI) in different age groups for both genders in Denmark over a 35-year period (1978-2012)., Methods and Results: Patients aged 30 years or older admitted with first MI in Denmark from 1978 to 2012 were included (n = 316 790). Overall, first MI incidence per 100 000 person-years (/105 p.y.) decreased significantly from 500 to 297/105 p.y. for males and from 229 to 156/105 p.y. for females. The decline was greatest among men aged 70-79 from 1460 to 643/105 p.y. (-56%). The majority of age groups also experienced declining incidence. However, men aged 30-39 and ≥90 years as well as females aged 30-49 and ≥90 years had increasing incidence during the study period. Moreover, the incidence decreased from 1978 to 1996 among males aged 40-49 and females aged 50-59 years, but increased in the remainder of the study period. One-year case-fatality declined significantly from 50 to 9% of MI male patients, and from 53 to 15% of MI female patients when comparing 1978 to 2012. Statistical analysis with Poisson models demonstrated that the mortality rate increased with age and decreased with time and indicated no significant difference between genders., Conclusions: During the period from 1978 to 2012, there was a significant decline in MI incidence among most age groups for both genders; however, an incidence increase was observed in men under 50 and women under 60 years, and ≥90 years for both genders. One-year case-fatality decreased constantly during the study period.

Objective: Schizophrenia is associated with a reduction of the lifespan by 20 years, with type II diabetes and cardiovascular disease contributing the most to the increased mortality. Unrecognised or silent myocardial infarction (MI) occurs in ~30% of the population, but the rates of unrecognised MI in patients with schizophrenia have only been sparsely investigated., Method: Electrocardiograms (ECG) from three psychiatric hospitals in Denmark were manually interpreted for signs of previous MI. Subsequently, ECGs were linked to the National Patient Registry in order to determine whether patients had a diagnosis consistent with previous MI., Results: A total of 937 ECGs were interpreted, 538 men (57.4%) and 399 women (42.6%). Mean age at the time of ECG acquisition was 40.6 years (95% CI: 39.7-41.5, range: 15.9-94.6). We identified 32 patients with positive ECG signs of MIs. Only two of these patients had a diagnosis of MI in the National Patient Registry. An additional number of eight patients had a diagnosis of MI in the Danish National Patient Registry, but with no ECG signs of previous MI. This means that 30 out of 40 (75%) MIs were unrecognised. Only increasing age was associated with unrecognised MI in a stepwise multiple logistic regression model compared with patients with no history of MI, OR: 1.03 per year of age, 95% CI: 1.00-1.06, p=0.021., Conclusion: Unrecognised MI is common among patients with schizophrenia and may contribute to the increased mortality found in this patient group.