Aim of database: The Danish Register of Chronic Obstructive Pulmonary Disease (DrCOPD) is a nationwide database aiming to describe the quality of treatment of all patients with chronic obstructive pulmonary disease (COPD) in Denmark. Study population: DrCOPD comprises data on all patients with a diagnosis of COPD. In the hospital setting, both in- and outpatients are included. In the setting of the general practice (GP), DrCOPD aims to include all patients with a COPD diagnosis who attend an annual control visit for COPD. Main variables: DrCOPD includes information on forced expiratory volume in 1 second, smoking status, body mass index, dyspnea, treatment modalities such as rehabilitation, smoking cessation, medical treatment, and the use of noninvasive ventilation during hospitalization due to exacerbations. The outcome variables include frequency of readmission and death 30 days after discharge from hospital. Descriptive data: Since 2008, the registration in the Danish hospitals has gradually become more comprehensive. In 2014, ~90% of 16,106 eligible patients had complete data sets that showed an improvement in the processes describing quality of care, including increased offering of smoking cessation, rehabilitation, and correct treatment with inhaled medication. Data from GPs have been included since 2011, but are still incomplete and comprise only ~20% of all COPD patients seen. The collection of data from GP settings has recently been hampered due to legislative controversies. Conclusion: In relatively few years, DrCOPD has become increasingly comprehensive and has documented an improvement in the management of COPD in Danish hospitals.

Background: Gender, possibly due to the influence of gonadal hormones, is presumed to play a role in the pathogenesis of multiple sclerosis (MS), but no studies have evaluated whether male infertility is associated with MS. Objective: To study the association between male factor infertility and prevalent as well as incident MS. Method: Our cohort was established by linkage of the Danish National in vitro fertilization (IVF) registry to The Danish Multiple Sclerosis Registry and consisted of 51,063 men whose partners had undergone fertility treatment in all public and private fertility clinics in Denmark between 1994 and 2015. Results: With a median age of 34 years at baseline, 24,011 men were diagnosed with male factor infertility and 27,052 did not have male factor infertility and made up the reference group. Men diagnosed with male factor infertility had a higher risk of prevalent (odds ratio (OR) = 1.61, 95% confidence interval (95% CI) 1.04–2.51) and incident MS (hazard ratio (HR) = 1.28, 95% CI 0.76–2.17) when compared to the reference group. Conclusion: This nationwide cohort study has shown, for the first time, an association between male infertility and MS which may be due to underlying common etiologies such as hypogonadism, shared genetics, or a joint autoimmune component.

STUDY QUESTION: What is the risk of death among men with oligospermia, unspecified male factor and azoospermia in the years following fertility treatment? SUMMARY ANSWER: No significantly elevated risk was observed among men with oligospermia and unspecified male factor, while an increased risk was found among men with azoospermia. WHAT IS KNOWN ALREADY: Previous studies have shown associations between male factor infertility and risk of death, but these studies have relied on internal reference groups and the risk of death according to type of male infertility is not well characterized. STUDY DESIGN, SIZE, DURATION: In this prospective record-linkage cohort study, we identified men who had undergone medically assisted reproduction (MAR) between 1994 and 2015. Data was linked to the Danish causes of death register and sociodemographic registers through personal identification numbers assigned to all Danish citizens at birth. PARTICIPANTS/MATERIALS, SETTING, METHODS: Men that had undergone MAR in Denmark (MAR Cohort; n = 64 563) were identified from the Danish IVF register, which includes data on whether infertility was due to male factor. For each man in the MAR cohort, five age-matched men who became fathers without fertility treatment were selected from the general population (non-MAR fathers; n = 322 108). Men that could not adequately be tracked in the Danish CPR register (n = 1259) and those that were censored prior to study entry (n = 993) were excluded, leaving a final population of 384 419 men. Risk of death was calculated by Cox regression analysis with age as an underlying timeline and adjustments for educational attainment, civil status and year of study entry. The risk of death was compared among men with and without male factor infertility identified from the IVF register (internal comparisons) as well as to the non-MAR fathers (external comparison). MAIN RESULTS AND THE ROLE OF CHANCE: The risk of death between the MAR cohort (all men, regardless of infertility) and the non-MAR fathers was comparable [hazard ratio (HR), 1.07; 95% CI, 0.98–1.15]. When the MAR cohort was limited to infertile men, these men were at increased risk of death [HR, 1.27; 95% CI, 1.12–1.44]. However, when stratified by type of male factor infertility, men with azoospermia had the highest risk of death, which persisted when in both the internal [HR, 2.30; 95% CI, 1.54–3.41] and external comparison [HR, 3.32; 95% CI, 2.02–5.40]. No significantly elevated risk of death was observed among men with oligospermia [HR, 1.14; 95% CI, 0.87–1.50] and unspecified male factor [HR, 1.10; 95% CI, 0.75–1.61] compared with the non-MAR fathers. The same trends were observed for the internal comparison. LIMITATIONS, REASONS FOR CAUTION: Duration of the follow-up was limited and there is limited generalizability to infertile men who do not seek fertility treatment. WIDER IMPLICATIONS OF THE FINDINGS: Using national health registers, we found an increased risk of death among azoospermic men while no increased risk was found among men with other types of infertility. For the azoospermic men, further insight into causal pathways is needed to identify options for monitoring and prevention. STUDY FUNDING/COMPETING INTEREST(S): This study is part of the ReproUnion collaborative study, co-financed by the European Union, Interreg V ÖKS. C.G.’s research stay at Stanford was funded by grants from the University of Copenhagen, Kong Christian den Tiendes Fond, Torben og Alice Frimodt Fond and Julie Von Müllen Fond. M.E. is an advisor for Sandstone and Dadi. All other authors declare no conflict of interests. TRIAL REGISTRATION NUMBER: Not relevant.