MR-Egger regression has recently been proposed as a method for Mendelian randomization (MR) analyses incorporating summary data estimates of causal effect from multiple individual variants, which is robust to invalid instruments. It can be used to test for directional pleiotropy and provides an estimate of the causal effect adjusted for its presence. MR-Egger regression provides a useful additional sensitivity analysis to the standard inverse variance weighted (IVW) approach that assumes all variants are valid instruments. Both methods use weights that consider the single nucleotide polymorphism (SNP)-exposure associations to be known, rather than estimated. We call this the `NO Measurement Error' (NOME) assumption. Causal effect estimates from the IVW approach exhibit weak instrument bias whenever the genetic variants utilized violate the NOME assumption, which can be reliably measured using the F-statistic. The effect of NOME violation on MR-Egger regression has yet to be studied.
An adaptation of the [Formula: see text] statistic from the field of meta-analysis is proposed to quantify the strength of NOME violation for MR-Egger. It lies between 0 and 1, and indicates the expected relative bias (or dilution) of the MR-Egger causal estimate in the two-sample MR context. We call it [Formula: see text] The method of simulation extrapolation is also explored to counteract the dilution. Their joint utility is evaluated using simulated data and applied to a real MR example.
In simulated two-sample MR analyses we show that, when a causal effect exists, the MR-Egger estimate of causal effect is biased towards the null when NOME is violated, and the stronger the violation (as indicated by lower values of [Formula: see text]), the stronger the dilution. When additionally all genetic variants are valid instruments, the type I error rate of the MR-Egger test for pleiotropy is inflated and the causal effect underestimated. Simulation extrapolation is shown to substantially mitigate these adverse effects. We demonstrate our proposed approach for a two-sample summary data MR analysis to estimate the causal effect of low-density lipoprotein on heart disease risk. A high value of [Formula: see text] close to 1 indicates that dilution does not materially affect the standard MR-Egger analyses for these data.
Care must be taken to assess the NOME assumption via the [Formula: see text] statistic before implementing standard MR-Egger regression in the two-sample summary data context. If [Formula: see text] is sufficiently low (less than 90%), inferences from the method should be interpreted with caution and adjustment methods considered.
There is increasing evidence supporting the relationship between family support and patient outcomes. Therefore, involving families in the care of cardiovascular patients is expected to be beneficial for patients. The quality of the encounter with families highly depends on the attitudes of nurses towards the importance of families in patient care.
The aim of this study was to describe the attitudes of nurses towards family involvement in patient care and to investigate the individual contributions of demographic, professional and regional background characteristics.
A survey was distributed among cardiovascular nurses attending an international conference in Norway and a national conference in Belgium. Nurses were asked to complete a questionnaire, including the Families' Importance in Nursing Care - Nurses' Attitudes scale. The study population consisted of respondents from Belgium ( n?=?348) and from Scandinavian countries (Norway, Sweden and Denmark; n?=?77).
In general, nurses viewed the family as important in care. However, attitudes towards actively inviting families to take part in patient care were less positive. Higher educational level and a main practice role in research, education or management were significantly associated with more positive attitudes. Furthermore, the attitudes of respondents living in Scandinavia were more positive as compared to the attitudes of respondents living in Belgium.
Education on the importance of families and active family involvement in patient care seems to be necessary in basic, undergraduate education, but also in clinical practice. More research is necessary in order to explore the cultural and regional differences in the attitudes of nurses towards the involvement of families in patient care.
All suicides for ages 20 years and younger in Manitoba from 1971 to 1982 were studied for demographic and risk factors. Major demographic findings for Caucasian Manitobans agreed with past studies but native children showed several fold the rates for Caucasian children matched for gender and age. Both native males and rural Caucasian males suicided significantly more frequently at younger ages than their urban counterparts. Significant risk factors and demographic clusters of suicide victims were determined by statistical means and the results discussed in terms of a better understanding of childhood suicide, on a psychodynamic basis.
Commentary on Svedlund M and Danileson E (2004) Myocardial infarction: narrations by afflicted women and their partners of lived experiences in daily life following an acute myocardial infarction. Journal of Clinical Nursing 13, 438-446.
Costs of screening a series of 18,152 newborn males for Duchenne muscular dystrophy (DMD) in Canada were evaluated. The final aim of neonatal screening for DMD is the avoidance of additional cases in the families identified. Total costs to avoid one case of DMD were estimated at Cdn. $172,000, while the incremental costs were found to be $83,000. Reagent costs, test sensitivity, efficacy of screening and compliance with genetic advice were identified as factors crucial for cost-effectiveness. Costs of neonatal screening for DMD are compared with costs of neonatal screening for inborn metabolic disorders. It is found that the two programmes are similar in costs. Earlier predictions of inordinate costs of screening for DMD are refuted.
Marked variation exists concerning the utilization of percutaneous coronary intervention (PCI) and coronary artery bypass grafting (CABG). The objective of this study was to examine differences in predictors of mode of revascularization across 3 provincial jurisdictions.
All patients who underwent PCI and isolated CABG in British Columbia, Alberta, and Nova Scotia between 1996 and 2007 were considered. Age- and sex-standardized rates of PCI and CABG per 100,000 population and PCI to CABG ratios were calculated by year and province. Logistic regression models were constructed to identify independent predictors of mode of revascularization in each province.
A total of 32,190 and 69,409 patients underwent CABG and PCI, respectively, during the study period. Significant increases in the age- and sex-adjusted PCI to CABG ratios were observed in all 3 provinces, but these ratios differed between provinces. Across all 3 jurisdictions, female sex and diagnosis of acute coronary syndrome favoured increased PCI vs CABG, and increased age, left main, or 3-vessel disease occurring before myocardial infarction, and diabetes favoured lower PCI vs CABG. After adjusting for clinical and angiographic factors, there remained a significant variation in choice of PCI vs CABG between the 3 provinces over time.
Significant interprovincial variability in PCI to CABG ratios was observed. Though certain patient-related factors predictive of either PCI or CABG were identified, factors beyond clinical presentation played a role in the choice of revascularization approach.
Recent research has identified younger women as an "at-risk" population with rising prevalence of cardiac risk factors and excess mortality risk following acute myocardial infarction (AMI). However, population-based data on trends in AMI hospitalization and early mortality post AMI among younger adults is scarce. We, therefore, aimed to provide a 10-year, descriptive analysis of these trends in a Canadian setting.
We assessed trends and sex differences in AMI hospitalization and 30-day mortality rates using negative binomial and logistic regression, respectively. From 2000 to 2009, there were 70,628 AMI hospitalizations in adults aged =20 years, in British Columbia, Canada, with 17.1% of cohort being younger adults =55 years. Overall, age-standardized AMI rates (per 100,000 population) declined similarly in men (295.8 to 247.7) and women (152.1 to 128.8) [sex-year interaction p=0.81]. However, these trends differed according to age (age-sex-year interaction p=0.02) with increased rates observed only in younger women (+1.7% per year; p=0.04). The 30-day mortality rates declined similarly for women (19.4% to 13.9%) and men (13.0% to 9.3%) (sex-year interaction p=0.33). Yet, younger women continued to have excess mortality risk, compared with younger men, even in the most recent period [odds ratio: (2008-09)=1.61 (95% onfidence interval: 1.25, 2.08)].
While the overall AMI hospitalization and 30-day mortality rates significantly declined in women and men, hospitalization rates in women =55 years increased and their excess risk of 30-day mortality persisted. These findings highlight the need to intensify strategies to reduce the incidence of AMI and improve outcomes after AMI in younger women.
The AIDS Prevention Street Nurse Program uses specially prepared community health nurses to focus on HIV and STD prevention with marginalized, hard-to-reach and high-risk clients within a broader context of harm reduction and health promotion. Street nurses (n = 17), service providers (n = 30), representatives of other HIV/STD programs in the province of British Columbia, Canada (N = 5), and clients (n = 32) were interviewed during an evaluation for the purpose of describing the nurses' work, the challenges the nurses' face, the fit of the program with other services, and the impact of the nurses' work. This article describes the impact of the nurses' work on clients. Impact/outcome changes reflected a progression from knowledge to behavioural levels and to major indicators of health/illness. Impact on clients included: knowing more about HIV/AIDS, their own situation, and options; receiving essential supplies to reduce harm and promote health; changing behaviour to reduce disease transmission, improve resistance, and promote health; connecting with help; feeling better about themselves and others; feeling supported; influencing others; receiving earlier attention for problems; being healthier with or without HIV; making major changes in drug use; and likely decreasing morbidity and mortality. The Program was found to be clearly effective in making a positive impact on clients.
ReprintIn: Can J Nurs Res. 2009 Mar;41(1):238-5819485055