Moving instead of asking? Performance-based tests and BASFI-questionnaire measure different aspects of physical function in ankylosing spondylitis

Introduction

Ankylosing Spondylitis (AS) is characterised by limitations in physical function. The Bath Ankylosing Spondylitis Functional Index (BASFI) is considered to be the gold-standard to assess physical function in AS patients. However, the BASFI questionnaire is a self-reported outcome measure and susceptible to subjective interpretation (under- or over-estimation). More objective outcome measures, like performance-based tests, could provide an objective outcome measurement for the evaluation of limitations in physical function. Therefore, the primary aim of this study was to determine the association between performance-based measures and the BASFI questionnaire.

Methods

In this cross-sectional study 126 AS patients completed the BASFI questionnaire and eight performance-based tests based on BASFI-items. Each test received three scores: one for performance (time or points) and a score for exertion and pain experienced during performance (using modified Borg-scale and VAS 0-100 mm, respectively). Linear regression analyses were used to assess the associations between the BASFI questionnaire and performance-based tests.

Results

The univariable association between performance and BASFI-score was moderate with a R-square of 0.31 and Beta of 0.56 (p's < 0.05). In a multivariable analysis, the association between performance, exertion and pain on the one hand and BASFI-score on the other was assessed; R-square increased to 0.54: the Beta's for exertion and pain during performance were 0.38 and 0.26, respectively; the Beta for performance decreased to 0.19 (p's < 0.05).

Conclusions

This study demonstrates that alongside actual performance, patients seem to incorporate exertion and pain in their assessment of perceived physical function on the BASFI questionnaire. Performance-based tests could provide an objective outcome measurement for the evaluation of physical function and give relevant new information in addition to the BASFI questionnaire.     

Designing a strategy to implement cost-effective blood transfusion management in elective hip and knee arthroplasties: A study protocol

ABSTRACT: BACKGROUND: Total hip and knee arthroplasties are two of the most commonly performed procedures in orthopedic surgery. Different blood-saving measures (BSMs) are used to reduce the often-needed allogenic blood transfusions in these procedures. A recent large randomized controlled trial showed it is not cost effective to use the BSMs of erythropoietin and perioperative autologous blood salvage in elective primary hip and knee arthroplasties. Despite dissemination of these study results, medical professionals keep using these BSMs. To actually change practice, an implementation strategy is needed that is based on a good understanding of target groups and settings and the psychological constructs that predict behavior of medical professionals. However, detailed insight into these issuses is lacking. Therefore, this study aims to explore which groups of professionals should be targeted at which settings, as well as relevant barriers and facilitators that should be taken into acount in the strategy to implement evidence-based, cost-effective blood transfusion management and to de-implement BSMs. METHODS: The study consists of three phases. First, a questionnaire survey among all Dutch orthopedic hospital departments and independent treatment centers (n?=?99) will be conducted to analyze current blood management practice. Second, semistructured interviews will be held among 10 orthopedic surgeons and 10 anesthesiologists to identify barriers and facilitators that are relevant for the uptake of cost-effective blood transfusion management. Interview questions will be based on the Theoretical Domains Interview framework. The interviews will be followed by a questionnaire survey among 800 medical professionals in orthopedics and anesthesiology (400 professionals per discipline) in which the identified barriers and facilitators will be ranked by frequency and importance. Finally, an implementation strategy will be developed based on the results from the previous phases, using principles of intervention mapping and an expert panel. DISCUSSION: The developed strategy for cost-effective blood transfusion management by de-implementing BSMs is likely to reduce costs for elective hip and knee arthroplasties. In addition, this study will lead to generalized knowledge regarding relevant factors for the de-implementation of non-cost-effective interventions and insight in the differences between implementation and de-implementation strategies.     

Power of the classical twin design revisited.

Statistical power of the classical twin design was revisited. The approximate sampling variances of a least-squares estimate of the heritability in a univariate analysis and estimate of the genetic correlation coefficient in a bivariate analysis were derived analytically for the ACE model. Statistical power to detect additive genetic variation under the ACE model was derived analytically for least-squares, goodness-of-fit and maximum likelihood-based test statistics. The noncentrality parameter for the likelihood ratio test statistic is shown to be a simple function of the MZ and DZ intraclass correlation coefficients and the proportion of MZ and DZ twin pairs in the sample. All theoretical results were validated using simulation. The derived expressions can be used to calculate power of the classical twin design in a simple and rapid manner.     

Microbial consumption of dimethyl sulfide and methanethiol in coastal marine sediments

Abstract: Samples were taken from oxic and anoxic zones of three ecosystems: a cyanobacterial mat, a diatom film and a carbonate sediment. Dimethylsulfide (DMS) concentrations were determined by headspace analysis of sediment slurries; maximal amounts were in the upper 5–10 mm of the sediments of 20 μM (cyanobacterial mat), 8 μM (diatom film) and < 1 μM in the carbonate sediment. Dissolved DMS in the cyanobacterial mat, determined by centrifugation and cryogenic trapping, was about two orders of magnitude lower than from slurry estimations but its variation with depth was similar. CH₃SH concentrations in slurried samples, determined after treatment with tributylphosphine, ranged from 2 to 7 μM in the diatom mat and was below the limit of detection (< 0.1 μM) in the carbonate sediment. MPN counts of bacteria that grew on DMS under oxic and anoxic (nitrate added) conditions were determined at all three sites. Aerobic DMS utilizers peaked in the surface and decreased with depth, while the population of anaerobic DMS utilizers was relatively constant in the top 20 mm. Populations of DMS utilizers were highest in the cyanobacterial mat and lowest in the carbonate sediment. MPN's of thiosulfate utilizers, aerobic and anaerobic (nitrate added) were determined in the cyanobacterial mat. Populations of aerobic and anaerobic S₂O₃²⁻ utilizers were similar throughout the top 20 mm and comparable to those of DMS utilizers in the top 5 mm, but higher by about 100-fold below that zone. DMS and CH₃SH consumption rates were measured in slurries of sediments and aerobic rates were similar or only slightly higher than anaerobic rates; the latter were stimulated by nitrate.     

The last African white giraffes live in farmers’ fields

The giraffe population (Giraffa camelopardalis) in Niger is the last representative of the peralta sub-species which lived throughout West Africa at the beginning of the twentieth century. Protected since the 1970s, giraffes cohabit with humans in cultivated landscapes. This may not have appeared to pose many problems in the past, but the relationship between farmers and giraffes has deteriorated with the expansion of cultivated land and that of the giraffe population, with reported cases of giraffes damaging crops. A survey was conducted in all the affected villages in the Kouré area to establish the nature, severity and distribution of the damage and to evaluate the local populations’ perception of the problem. Cowpeas are fed upon in the field at harvest time and in the granaries, as well as ripe mangoes, during the most critical period for giraffes’ nutrition. The vast majority of farmers interviewed consider giraffes to be rather a problem in spite of tourism revenues they can obtain from them. This opinion has individually little correlation with damage rate on crops or easy access to tourism revenues. The damage risk factors are first and foremost considered as uncontrollable by the farmers, even if technical protection measures could easily be put in place locally. The inter-relationships between the socio-economic context and the way the problem is perceived are discussed.     

Characteristics and turnover of exopolymeric substances in a hypersaline microbial mat

The properties and microbial turnover of exopolymeric substances (EPS) were measured in a hypersaline nonlithifying microbial mat (Eleuthera, Bahamas) to investigate their potential role in calcium carbonate (CaCO₃) precipitation. Depth profiles of EPS abundance and enzyme activities indicated that c . 80% of the EPS were turned over in the upper 15–20 mm. Oxic and anoxic mat homogenates amended with low-molecular-weight (LMW) organic carbon, sugar monomers, and different types of EPS revealed rapid consumption of all substrates. When comparing the consumption of EPS with that of other substrates, only marginally longer lag times and lower rates were observed. EPS (5–8%) were readily consumed during the conversion of labile to refractory EPS. This coincided with a decrease in glucosidase activity and a decrease in the number of acidic functional groups on the EPS. Approximately half of the calcium bound to the EPS remained after 10 dialyses steps. This tightly bound calcium was readily available to precipitate as CaCO₃. We present a conceptual model in which LMW organic carbon complexed with the tightly bound calcium is released upon enzyme activity. This increases alkalinity and creates binding sites for carbonate and allows CaCO₃ to precipitate. Therefore, this model explains interactions between EPS and CaCO₃ precipitation, and underscores the critical role of aerobic and anaerobic microorganisms in early diagenesis and lithification processes.     

Variation in the dysbindin gene and normal cognitive function in three independent population samples

The association between DTNBP1 genotype and cognitive abilities was investigated in three population samples (1054 Scottish, 1806 Australian and 745 English) of varying age. There was evidence in each of the cohorts for association ( P  <  0.05) to single nucleotide polymorphisms ( SNPs) and haplotypes previously shown to relate to cognition. By comparison with previous findings, these associations included measures of memory, and there was at best equivocal evidence of association with general cognitive ability. Of the SNPs typed in all three cohorts, rs2619528 and rs1011313 showed significant association with measures of executive function in two cohorts, rs1018381 showed significant association with verbal ability in one cohort and rs2619522 showed significance/marginal significance with tests of memory, speed and executive function in two cohorts. For all these SNPs, the direction and magnitude of the allelic effects were consistent between cohorts and with previous findings. In the English cohort, a previously untested SNP (rs742105) located in a distinct haplotype block upstream of the other SNPs showed the strongest significance ( P  <  0.01) for measures of memory but weaker significance for general cognitive ability. Our results therefore support involvement of the dysbindin gene in cognitive function, but further work is needed to clarify the specific functional variants involved and the cognitive abilities with which they are associated.     

"Silent" sites in Drosophila genes are not neutral: evidence of selection among synonymous codons

The patterns of synonymous codon usage in 91 Drosophila melanogaster genes have been examined. Codon usage varies strikingly among genes. This variation is associated with differences in G+C content at silent sites, but (unlike the situation in mammalian genes) these differences are not correlated with variation in intron base composition and so are not easily explicable in terms of mutational biases. Instead, those genes with high G+C content at silent sites, resulting from a strong "preference" for a particular subset of the codons that are mostly C- ending, appear to be the more highly expressed genes. This suggests that G+C content is reduced in sequences where selective constraints are weaker, as indeed seen in a pseudogene. These and other data discussed are consistent with the effects of translational selection among synonymous codons, as seen in unicellular organisms. The existence of selective constraints on silent substitutions, which may vary in strength among genes, has implications for the use of silent molecular clocks.