The coexistence of terms to describe the presence of multiple concurrent diseases

Background: Consensus on terminology for multiple diseases is lacking. Because of the clinical relevance and social impact of multiple concurrent diseases, it is important that concepts are clear. Objective: To highlight the diversity of terms in the literature referring to the presence of multiple concurrent diseases/conditions and make recommendations. Design: A bibliometric analysis of English-language publications indexed in the MEDLINE database from 1970 to 2012 for the terms comorbidity, multimorbidity, polymorbidity, polypathology, pluripathology, multipathology, and multicondition, and a review of definitions of multimorbidity found in English-language publications indexed from 1970 to 2012 in the MEDLINE and SCOPUS databases. Results: Comorbidity was used in 67,557 publications, multimorbidity in 434, and the other terms in three to 31 publications. At least 144 publications used the term comorbidity without referring to an index disease. Thirteen general definitions of multimorbidity were identified, but only two were frequently used (91% of publications). The most frequently used definition (48% of publications) was “more than one or multiple chronic or long-term diseases/conditions”. Multimorbidity was not defined in 51% of the publications using the term. Conclusions: Comorbidity was overwhelmingly used to describe any clinical entity coexisting with an index disease under study. Multimorbidity was the term most frequently used when no index disease was designated. Several definitions of multimorbidity were found. However, most authors using the term did not define it. The use of clearly defined terms in the literature is recommended until a general consensus on the terminology of multiple coexistent diseases is reached.Journal of Comorbidity 2013;3(1):4–9 

Improving the external validity of clinical trials: the case of multiple chronic conditions

The U.S. Department of Health and Human Services vision and strategic framework on multiple chronic conditions (MCCs) incorporates recommendations designed to facilitate research that will improve our knowledge about interventions and systems that will benefit individuals with MCCs (or multimorbidity). The evidence base supporting the management of patients with MCCs will be built both through intervention trials specifically designed to address multimorbidity and identification of MCCs in participants across the clinical trial range. This article specifically focuses on issues relating to external validity with specific reference to trials involving patients with MCCs. The exclusion of such patients from clinical trials has been well documented. Randomized control trials (RCTs) are considered the “gold standard” of evidence, but may have drawbacks in relation to external validity, particularly in relation to multimorbidity. It may, therefore, be necessary to consider a broader range of research methods that can provide converging evidence on intervention effects to address MCCs. Approaches can also be taken to increase the usefulness of RCTs in general for providing evidence to inform multimorbidity management. Additional improvements to RCTs would include better reporting of inclusion and exclusion criteria and participant characteristics in relation to MCCs. New trials should be considered in terms of how they will add to the existing evidence base and should inform how interventions may work in different settings and patient groups. Research on treatments and interventions for patients with MCCs is badly needed. It is important that this research includes patient-centered measures and that generalizability issues be explicitly addressed.Journal of Comorbidity 2013;3(2)30–3

VSAERO analysis of tip planforms for the free-tip rotor

The results of a numerical analysis of two interacting lifting surfaces separated in the spanwise direction by a narrow gap are presented. The configuration consists of a semispan wing with the last 32 percent of the span structurally separated from the inboard section. The angle of attack of the outboard section is set independently from that of the inboard section. In the present study, the three-dimensional panel code VSAERO is used to perform the analysis. Computed values of tip surface lift and pitching moment coefficients are correlated with experimental data to determine the proper approach to model the gap region between the surfaces. Pitching moment data for various tip planforms are also presented to show how the variation of tip pitching moment with angle of attack may be increased easily in incompressible flow. Calculated three-dimensional characteristics in compressible flow at Mach numbers of 0.5 and 0.7 are presented for new tip planform designs. An analysis of sectional aerodynamic center shift as a function of Mach number is also included for a representative tip planform. It is also shown that the induced drag of the tip surface is reduced for negative incidence angles relative to the inboard section. The results indicate that this local drag reduction overcomes the associated increase in wing induced drag at high wing lift coefficients

The experience of adults with multimorbidity: a qualitative study

Background: Findings from several countries indicate that the prevalence of multimorbidity is very high among clients of primary healthcare. A deeper understanding of patients’ experiences from their own perspective can greatly enrich any intervention to help them live as well as possible with multimorbidity. Objective: To describe the fundamental structure of adults’ experience with multimorbidity. Design: A phenomenological study was undertaken to describe the experiences of 11 adults with multimorbidity. These adults participated in two semi-structured interviews, the content of which was rigorously analyzed. Results: At the core of the study participants’ multimorbidity experience are the impression of aging prematurely, difficulties with self-care management, and issues with access to the healthcare system, which contribute to the problem’s complexity. Despite these issues, participants with multimorbidity report attempting to take control of their situation and adjusting to daily living. Conclusions: The description of this experience, through the systemic vision of participants, provides a better understanding of the realities experienced by people with multimorbidity.Journal of Comorbidity 2014;4(1):11–2

Secondary analysis of data on comorbidity/multimorbidity: a call for papers

Despite the high proportion and growing number of people with comorbidity/multimorbidity, clinical trials often exclude this group, leading to a limited evidence base to guide policy and practice for these individuals [1–5]. This evidence gap can potentially be addressed by secondary analysis of studies that were not originally designed to specifically examine comorbidity/multimorbidity, but have collected information from participants on co-occurring conditions. For example, secondary data analysis from randomized controlled trials may shed light on whether there is a differential impact of interventions on people with comorbidity/multimorbidity. Furthermore, data regarding comorbidity/multimorbidity can often be obtained from registration networks or administrative data sets

Le système monétaire européen : Un point de vue nord américain

Is the european monetary System (EMS) a useful approach to the problems it is meant to solve and to the pursuit of the objectives that its promoters have set for themselves? A review by the authors of a number of economic motives which underly the creation of the EMS leads them to conclude that the various economic problems which the european readily blame on floating exchange rates find in fact their origins in the economic policies pursued by the national governments. Moreover, the authors consider that the defense of parities in the EMS, either through intervention in the exchange markets or by other means, can involve high economic costs and that in the longer run market forces always triumph when parities no longer reflect the fundamental positions of the respective economies. Among the other factors which limit the usefulness of the EMS the authors identify the continuing lack of macro-economic policy coordination by participating countries, its regional character, the underestimation of the importance of the american dollar in the international monetary system and the impact of its fluctuations on european currencies and the tendency of the EMS to harmonize inflation rates at a higher level than should be aimed for. The authors therefore conclude that it is doubtful that the EMS constitutes a useful instrument of economic policy and that efforts towards european monetary union based on such a system of parities can be successful under present circumstances

Comparative assessment of three different indices of multimorbidity for studies on health-related quality of life

BACKGROUND: Measures of multimorbidity are often applied to source data, populations or outcomes outside the scope of their original developmental work. As the development of a multimorbidity measure is influenced by the population and outcome used, these influences should be taken into account when selecting a multimorbidity index. The aim of this study was to compare the strength of the association of health-related quality of life (HRQOL) with three multimorbidity indices: the Cumulative Illness Rating Scale (CIRS), the Charlson index (Charlson) and the Functional Comorbidity Index (FCI). The first two indices were not developed in light of HRQOL. METHODS: We used data on chronic diseases and on the SF-36 questionnaire assessing HRQOL of 238 adult primary care patients who participated in a previous study. We extracted all the diagnoses for every patient from chart review to score the CIRS, the FCI and the Charlson. Data for potential confounders (age, sex, self-perceived economic status and self-perceived social support) were also collected. We calculated the Pearson correlation coefficients (r) of the SF-36 scores with the three measures of multimorbidity, as well as the coefficient of determination, R(2), while controlling for confounders. RESULTS: The r values for the CIRS (range: -0.55 to -0.18) were always higher than those for the FCI (-0.47 to -0.10) and Charlson (-0.31 to -0.04) indices. The CIRS explained the highest percent of variation in all scores of the SF-36, except for the Mental Component Summary Score where the variation was not significant. Variations explained by the FCI were significant in all scores of SF-36 measuring physical health and in two scales evaluating mental health. Variations explained by the Charlson were significant in only three scores measuring physical health. CONCLUSION: The CIRS is a better choice as a measure of multimorbidity than the FCI and the Charlson when HRQOL is the outcome of interest. However, the FCI may provide a good option to evaluate the physical aspect of HRQOL for the ease in its administration and scoring. The Charlson index may not be recommended as a measure of multimorbidity in studies related to either physical or mental aspects of HRQOL

Enhancing research quality and reporting: why the Journal of Comorbidity is now publishing study protocols

The Journal of Comorbidity was launched in 2011 and has since become established as a high-quality journal that publishes open-access, peer-reviewed articles, with a focus on advancing the clinical management of patients with comorbidity/multimorbidity. To further enhance research quality and reporting of studies in this field, the journal is now offering authors the opportunity to publish a summary of their study protocols – a move designed to generate interest and raise awareness in ongoing clinical research and to enable researchers to detail their methodologies in order that replication by scientific peers is possible