Designing randomised controlled trials in rheumatology – What,why, and how

Randomised controlled trials (RCTs) have become the workhorse for evaluating efficacy of various healthcare interventions. The basic plan is to compare the outcome experience of two or more prognostically similar groups of patients with study intervention being the only difference between them. It involves key elements such as random allocation, concealment of allocation, and blinding to guard against design-related biases. This article explains these key features and the steps involved in designing an RCT in the context of rheumatological diseases.     

The curious case of cyberchondria: A longitudinal study on the reciprocal relationship between health anxiety and online health information seeking

The current study is the first to longitudinally investigate the reciprocal relationship between online health information seeking and health anxiety, i.e., cyberchondria. Expectations were that health anxious individuals who go online to find health information, experience an increase in health anxiety, which in turn will reinforce online seeking. A 4-wave longitudinal survey study among 5322 respondents aged 16–93 was conducted. Our results showed that individuals who are more health anxious than others, search online for health information more. Moreover, the results provided initial evidence for the expected reciprocal relationship between health anxiety and online health information seeking in respondents with non-clinical levels of health anxiety at the start of the study. However, this reciprocal relationship could not be found in a subsample of clinically health anxious individuals. Although for these individuals online health information seeking did not seem to exacerbate health anxiety levels, it might still serve as a maintaining factor of clinical health anxiety.     

A short-term mineral amendment impacts the mineral weathering bacterial communities in an acidic forest soil

Mineral amendment (i.e. calcium, phosphorous, potassium and/or magnesium) is a management practice used in forestry to improve nutrient availability and recover soil fertility, especially in nutrient-poor forest ecosystems. However, whether this amendment can lead to modifications of the soil characteristics and an improvement in tree growth, and its impact on the soil bacterial communities, especially the mineral weathering bacterial communities, remains poorly documented. In this study, we investigated the short-term impact of a mineral amendment on the taxonomic and functional structure of the mineral weathering bacterial communities. To do this, a plantation of four-year old oak (Quercus petraea) trees amended with or without dolomite [CaMg(CO₃)₂] was established in the experimental forest site of Breuil-Chenue, which is characterized by an acidic soil and a low availability of calcium and magnesium. Three years after amendment, soil samples were used to isolate bacteria as well as to determine the soil characteristics and the metabolic potentials of these soil microbial communities. Based on a bioassay for quantifying the solubilisation of inorganic phosphorous, we demonstrate that the bacterial isolates coming from the non-amended bulk soil were significantly more efficient than those from the amended bulk soil. No difference was observed between the bacterial isolates coming from the amended and non-amended rhizospheres. Notably, the taxonomic analyses revealed a dominance of bacterial isolates belonging to the Burkholderia genus in both samples. Overall, our results suggest that the bioavailability of nutritive cations into soil impacts the distribution and the efficacy of mineral weathering bacterial communities coming from the soil but not those coming from the rhizosphere.     

STEM DISTRIBUTION IN IRREGULAR FORESTS

The author outlines the fifty years history of national professional forestry education in Canberra by the Australian Forestry School and its successor the Australian National University Department of Forestry.     

Retrospective Analyses for Hypothesis Generation A Commentary on the Pack Trial (Prevention of Atherosclerotic Complications with Ketanserin)

Publication of the results of a large-scale randomized control trial (RCT) of the anti-serotonin drug ketanserin in patients with intermittent claudication offers an opportunity to examine the validity of retrospective subgroup analyses to generate hypotheses for further validation. This was prompted by an unanticipated adverse interaction which occurred in a subgroup of patients receiving both ketanserin and potassium-losing diuretics. The quality of the study ranked it in the 99th percentile of over 400 RCTs evaluated by a quality scoring system. The subgroup analysis resulted from the emergence during the study of a highly significant excess mortality in the patients on diuretics (relative risks 0.88 for those on ketanserin alone, 0.95 on potassium-sparing and 2.44 for those on potassium-losing diuretics (P = 0.007). External validity was evident from data in the literature indicating that a rare tendency of the many drugs that prolong the QT interval to cause torsade de pointes and fatal arrhythmias is exacerbated by hypokalemia of the degree caused by potassium losing diuretics. When the keganserin and-placebo treated Ratients also on potassium-losing diuretics are removed from the analyses there is a 23% reduction iri endpoints which the power is no longer sufficient to detect as significant. There is also an apparent lag phase. Further study of the drug is clearly indicated.     

Competition for nitrogen between trees in a mixed-species plantation in the Solomon Islands

ABSTRACT

As part of an ACIAR project aiming at improving community forestry in Solomon Islands, mixed-species plantations were established to assess the feasibility of inter-planting teak (Tectona grandis L. f.) and flueggea (Flueggea flexuosa Muell. Arg). Flueggea is a native hardwood used for timber and fence construction, and early removal of flueggea from a mixed-species stand could have a similar silvicultural outcome to thinning a single-species stand of teak. Using ¹⁵N-labelled ammonium sulphate, we investigated the competition for nitrogen (N) between the two species. The ¹⁵N-labelled tracer was applied to the soil surface of plots containing pairs of trees, one of each species, in 2-year-old and 4-year-old mixed-species stands, after the pairs of trees were isolated from the rest of the stand by an impermeable membrane. After 12–18 months, the isolated trees were measured and harvested, and each tree component (roots, stem, branch and foliage) was weighed and analysed for total N and ¹⁵N enrichment. There was no significant difference in the amounts of ¹⁵N between teak and flueggea components at either age, suggesting equal uptake of added ¹⁵N-labelled tracer by both species. The ¹⁵N amount was greater in stem followed by root, foliage and branch for teak and branch followed by stem, root and foliage for flueggea. About 42% and 55% of the applied ¹⁵N tracer were recovered in the 2-year and 4-year plots respectively, suggesting that higher uptake occurs with well-established root structure and that N losses decreased following canopy closure. The amount of total nitrogen was not significantly different between teak and flueggea components at age 2 and 4 years, and may indicate equal access to growth resources, and similar allocation. Although teak had significantly greater stem growth (height, basal area and volume) than flueggea in the 4-year plots, ¹⁵N uptake were similar to flueggea, which may mean that competition for growth resources was still minimal or that access to the resources was equal and growth rates differed between species.     

协定肢伤Ⅰ方口服、热敷治疗四肢闭合损伤大样本随机平行对照研究

[目的]观察协定肢伤I方口服热敷治疗四肢闭合损伤疗效。[方法]使用大样本随机平行对照方法,将2468例门诊及住院患者按掷骰子法随机分为两组。对照组1212例协定肢伤I方(红花、延胡索各15g,桃仁、川芎、赤芍、生三七粉另包冲服、当归、泽泻、桂枝、牛膝、山楂各10g),1剂/d,水煎300mL,早晚温服;蜡疗机熬化粗石蜡装塑料袋敷于患处,12h/次。治疗组1256例协定肢伤I方药渣加水送入湿热敷机内与敷布同煮30min,于伤后或术后24h将敷布外套棉布贴敷于伤处,30min/次,2次/d;协定肢伤I方口服同对照组。连续治疗7d为1疗程。观测临床症状、疼痛积分、肿胀指数、不良反应。治疗1疗程,判定疗效。[结果]治疗组痊愈922例,显效248例,有效63例,无效23例,总有效率98.16%。对照组痊愈705例,显效278例,有效105例,无效124例,总有效率89.76%。治疗组疗效优于对照组(P0.05)。相关指标两组均有改善(P0.05),治疗组改善优于对照组(P0.05)。[结论]协定肢伤I方口服热敷治疗四肢闭合损伤效果显著,值得推广。     

Stochastically-modulated stimulation to slow down muscle fatigue at stimulated sites in paraplegics using functional electrical stimulation for leg extension

Abstract

This short communication is a preliminary report on a study concerning slowing down the rate of muscle fatigue when FES (Functional Electrical Stimulation) is applied for standing and walking by complete (traumatic) thoracic-level paraplegics. It is shown that randomly modulating the inter-pulse interval between FES pulses (which serve to trigger action potentials in the peripheral nerves concerned) re~lJlts in a significantly lower rate ofmuscle fatigue, as tested in a series ofleg extensions, when FES was applied at the quadriceps. Specifically, we report that the best results (longest durations of leg extension prior to onset of muscle-fatigue) were achieved with a ± 5 msec uniformly-distributed (pseudo-) white-noise modulation at a 42 msec inter-pulse interval (24 pulses per sec). These resulted in an average increase in duration of leg extension ofapproximately 37% in this pilot study, as compared with unmodulated (fixed-rate) trains ofFES pulses. This significant increase, even in a very preliminary study appears to merit careful further examination, since it may allow a possibly significant increase in standing duration and in walking range of paraplegics using FES for ambulation. [Neural Res 2000; 22: 703-704]     

Logging residue assessment by line intersect sampling

Line intersect sampling is applied in various aspects of forest management. One of the more common applications is to estimate the quantity of logging residue remaining on the ground following harvesting operations. The estimate of residue quantity can be used to develop residue models for yield prediction and to monitor harvesting operations to ensure prescribed utilisation levels are achieved. The application of line intersect sampling to quantifying logging residue has not always been as efficient as may be desired.

Alternatives to the traditional application of the method have been developed using regular polygons with odd numbers of sides and circular sample lines. These shapes are more robust in overcoming the bias in the orientation of logging residue. Monte Carlo simulation was used to develop a model to predict the sample size required to achieve a specified precision of the estimate of residue for nine-sided polygonal (nonagonal) sample lines. Budget functions derived from time studies of logging residue assessment trials provide the basis for planning assessment programs. The improved method is applied to radiata pine (Pinus radiata D.Don) plantations managed in South Australia by Primary Industries South Australia (PISA) Forestry and CSR Softwoods.     

Early Growth of Radiata Pine in Relation to a Land Classification System on Forestier Peninsula in Tasmania

A land classification dividing the forest area of Forestier Peninsula in south eastern Tasmania into two land systems, the Blackman land system and the Murdunna land system, and several land units is described. Results from a trial to evaluate four component units of the land classification for establishment of a radiata pine plantation indicate different growth rates, nutrient deficiencies and responses on different units. On three of the four units there was a growth response to application of phosphorus and an interaction of nitrogen and phosphorus. On the fourth unit there was no growth response to application of phosphorus alone but there was a response to application of nitrogen and phosphorus together. Without treatment, radiata pine trees growing on the Murdunna land system had extremely low foliar concentrations of phosphorus, nitrogen and copper. On only one land unit was growth satisfactory without fertilizer.