Risk for hip fracture before and after total knee replacement in Sweden.

We studied the risk for hip fracture before and after total knee replacement (TKR) in the entire population in Sweden. Women and men had a low risk for hip fracture before TKR but an increased risk the first year after TKR. PURPOSE: It is known that osteoarthritis is associated with high bone mass. We therefore studied the risk of hip fracture before and after total knee replacement (TKR), risk of different hip fracture types, and risk subdivided in genders and age groups. METHODS: We followed the total Swedish population born between 1902 and 1952 (n = 4,258,934) during the period 1987-2002 and identified all patients with TKR due to primary OA (n = 39,291), and all patients with hip fracture (n = 195,860) in the Swedish National Inpatient Register. The risk time analyses were based on Poisson regression models. RESULTS: The hazard ratio (HR) for hip fracture the last year before TKR was 0.86 (95% CI 0.74 to 1.00) and the first year after 1.26 (95% CI 1.11 to 1.42) compared to individuals without TKR. The HR for femoral neck fracture 0-10 years after TKR was 0.95 (95% CI 0.89 to 1.01) and for trochanteric fracture was 1.13 (95% CI 1.06 to 1.21). The HR for hip fracture in the age group 50-74 was 1.28 (95% CI 1.14 to 1.43) and in the age group 75-90 years was 0.99 (95% CI 0.94 to 1.04) 0-10 years after TKR, compared to individuals without TKR. CONCLUSION: Individuals had a low risk for hip fracture before TKR but an increased risk the first year after TKR. The risk in individuals below age 75 years and for trochanteric fractures was increased after TKR. Possible explanations include changed knee kinematics after a TKR, physical activity level, fall risk, and other unknown factors.

Increased risk for hip fracture after death of a spouse-further support for bereavement frailty?

Death of a spouse is associated with poorer physical and mental health. We followed all married individuals, born from 1902 to 1942, during the period from 1987 to 2002, and found that widows and widowers had higher risk for hip fracture, compared with still married women and men. INTRODUCTION: Spousal bereavement can lead to poorer physical and mental health. We aimed to determine whether married women and men had an elevated risk of hip fracture after death of a spouse. METHODS: In a retrospective cohort study, we followed all Swedish married individuals aged 60 to 100 years (n = 1,783,035), from 1987 to 2002. Data are presented as mean with 95% confidence interval (CI). RESULTS: During the follow-up period, 21,305 hip fractures among widows and 6538 hip fractures among widowers were noted. The hazard ratio (HR) for hip fracture in widows compared with married women was 1.34 (95% CI 1.31 to 1.37) and for widowers compared with married men 1.32 (95% CI 1.29 to 1.35). The HR for hip fracture in the first 6 months after death of a spouse was in widows compared with married women 1.62 (95% CI 1.53 to 1.71) and in widowers compared with married men 1.84 (95% CI 1.68 to 2.03). The elevated risk was especially prominent in young widowers in the age range 60-69 years. During the first 6 months they showed a HR of 2.76 (95% CI 1.66 to 4.58) for a hip fractvure compared with age matched married men. Widows aged 60-69 years showed a HR of 1.59 (95% CI 1.26 to 1.99) compared with age matched married women. CONCLUSION: Our observation of a higher hip fracture risk in both genders in connection with the death of a spouse indicates a possible effect of bereavement on frailty.

Neural inhibition can explain negative BOLD responses: A mechanistic modelling and fMRI study.

Functional magnetic resonance imaging (fMRI) of hemodynamic changes captured in the blood oxygen level-dependent (BOLD) response contains information of brain activity. The BOLD response is the result of a complex neurovascular coupling and comes in at least two fundamentally different forms: a positive and a negative deflection. Because of the complexity of the signaling, mathematical modelling can provide vital help in the data analysis. For the positive BOLD response, there are plenty of mathematical models, both physiological and phenomenological. However, for the negative BOLD response, no physiologically based model exists. Here, we expand our previously developed physiological model with the most prominent mechanistic hypothesis for the negative BOLD response: the neural inhibition hypothesis. The model was trained and tested on experimental data containing both negative and positive BOLD responses from two studies: 1) a visual-motor task and 2) a working-memory task in conjunction with administration of the tranquilizer diazepam. Our model was able to predict independent validation data not used for training and provides a mechanistic underpinning for previously observed effects of diazepam. The new model moves our understanding of the negative BOLD response from qualitative reasoning to a quantitative systems-biology level, which can be useful both in basic research and in clinical use.

Publications on dementia in Medline 1974-2009: a quantitative bibliometric study.

OBJECT: The aim is to describe the development of the scientific literature on dementia. METHODS: We present a quantitative, bibliometric study of the literature on dementia, based on Medline, covering 36 years (1974-2009). Two samples of references to dementia papers were retrieved: The main sample based on the MeSH term Dementia holds more than 88,500 references. We have compared the annual additions of references on dementia with the addition to total Medline. Changes of 'the Dementia to Medline ratio' (%) give the best information on the development. RESULTS: Publications on dementia increased 5.6 times faster than Medline. Most of this relative acceleration took place during 1980-1997, when the references on dementia increased from 0.17 to 0.78%. During the recent 12 years, the publications on dementia have been keeping pace with Medline and have stabilized around 0.8%. CONCLUSIONS: We have shown a large increase of the literature on dementia, relative both to the development of all medical research and to all psychiatric research. The bibliometric approach may be questioned as quantitative methods treat articles as being of equal value, what is not true. If, for example, during a certain period, the research output is 'inflated' by a great number of repetitive papers, the quantitative method will give an unfair picture of the development. Our relative method, however, will give relevant results as, at each point of time, the proportion of 'valuable research' ought to be about the same in the dementia group as in total Medline.

Schizophrenia in Medline 1950-2006: a bibliometric investigation.

The aim was to perform a bibliometric study, and compare the quantity of publications on schizophrenia with the total medical literature in Medline during 57 years, 1950-2006. The annual additions of literature to Medline are continually increasing and form the Medline growth curve. Comparisons of the number of publications on schizophrenia, or any other disease, to this curve, may be used to estimate the research activity. Methods for the identification of relevant references to papers on schizophrenia were evaluated and three different samples were operationally defined, retrieved and counted. During 1950-2006, 16.28 million references were added to Medline. Nearly 68000, 0.42%, references were related to schizophrenia. The percentage of papers on schizophrenia among the psychiatric literature decreased from 5.2 to 2.6%. The present study indicates that the number of references on schizophrenia in Medline has followed the general increase of medical publications. This pattern differs compared to some other research fields such as dementia, HIV, and peptic ulcer. Samples of references on schizophrenia may be retrieved in Medline by operational definitions of search methods. The quantity of schizophrenia research during 57 years has kept pace with the total medical literature. One interpretation of the results is that more resources are needed to enhance research activities on schizophrenia.

The use of PubMed/Medline in psychiatry. 1: Presentation of NLM and PubMed.

A comprehensive view of the available literature on a psychiatric problem can be found in the large electronic databases. Medline at the National Library of Medicine (NLM) in USA is the largest medical database. PubMed is the searchable database at the NLM, having Medline as its major content. PubMed is free of charge, barrier-free and always accessible via the Internet. This paper describes the NLM, Medline and PubMed. The indexing of scientific papers in Medline is based on Medical Subject Headings, the MeSH terms. The hierarchic tree structure of MeSH is the basis of the search and retrieval system. The present paper is the first in a series of three, intended as a tutorial on the use of PubMed for inexperienced users. Information and examples on the MeSH system, together with exercises in its use, are presented in an appendix.

The use of PubMed/Medline in psychiatry. 2: The PubMed search window: a description and a tutorial.

A previous paper, in a series of three, presented the National Library of Medicine, Medline, PubMed and the MeSH system. Connection to PubMed via the Internet opens the PubMed search window that is the tool for retrieving references to scientific medical literature. This paper is intended as a tutorial for an inexperienced visitor to PubMed, and describes the search window in some detail. Several proposals for exercises in its use are given in the text, while explanations and comments to the exercises are presented in an appendix. The following procedures are described: retrieving references, ways to see the abstract, ways of displaying, sorting and showing the references, together with how to produce lists, import references to your own computer, and ways to get the full text of a paper.

The use of PubMed/Medline in psychiatry. 3: Searching PubMed.

This paper is the third in a series of three, intended as a tutorial in the use of PubMed/Medline for an inexperienced user. The papers have the following contents: I--a description of NLM, Medline, PubMed and the system of Medical Subject Headings (MeSH), which form the basis for the indexing of scientific articles, books and other items at NLM. II--A description and a tutorial of the PubMed search window. III--The present article deals mainly with the searching for references in PubMed. Ways of restricting and concentrating the search are presented, and exercises are proposed. A reader may also find guidance for a search for medical books in the NLM Catalog, and in the use of tools like Related Articles, Bookshelf, and Index. With eating disorders as an example, more information is presented on the use of MeSH terms.