OBJECTIVE: To test the null hypothesis that clinical dental trials with adequate random sequence generation together with adequate allocation concealment do not differ in their effect size from trials lacking adequate concealment. STUDY DESIGN AND SETTING: The oral health section of the Cochrane database was searched online until 20 July 2011. All listed entries, except reviews in protocol stage and duplications, were included. Included systematic reviews were accepted for data extraction ...
CONTEXT: The dichotomous outcome of a clinical intervention may be defined as success versus failure and subsequently expressed in the number of intervention successes and failures. Success and failure numbers of two clinical interventions may be compared and the resulting effect estimate expressed either as Risk ratio (RR) or Odds ratio (OR) with 95% confidence intervals (CI). The expression of effect estimates in Risk ratio appears to be easier to interpret. Also, Risk ratio of success ...
CONTEXT: Selection bias interferes with the internal validity of clinical trials and leads to favoring one clinical outcome over another. Random sequence generation and allocation concealment of such sequence have been proposed to limit the risk of selection bias. However, selection bias can be introduced based on knowledge of the directly observed random sequence when allocation concealment is subverted. Such subversion may statistically be detected in randomised control trials with dich...
CONTEXT: Systematic review evidence provides best justification for specific beliefs regarding clinical interventions. The degree of such belief depends on the precision and internal validity of the evidence. While precision is often achieved on basis of quantification and statistical analysis, the (internal) validity of the evidence is appraised through judgement of the risk for several known biases. Against the background of the subsequent results, a conclusion is formulated in answer t...
CONTEXT: Clinical knowledge, as any other type of knowledge, can be regarded as justified belief. The justification of belief follows two cognitive strategies: coherence of logic and correspondence of facts. PROBLEM: Coherence strategy has been traditionally favoured in the justification of beliefs concerning medical interventions throughout the centuries and is today still preferred by many clinicians as providing “logical sense” for or against the application of therapies, diagnostic...
CONTEXT: Selection bias interferes with the internal validity of clinical trials and leads to favouring one clinical outcome over another. In order to limit the influence of selection bias on clinical trials, the methodological interventions: random sequence generation and allocation concealment of such sequence have been proposed. Subsequently, authors of systematic reviews judge risk of selection bias in trials according to the reported details concerning how random sequence generation ...
CONTEXT: Selection bias interferes with the internal validity of clinical trials and leads to favoring one clinical outcome over another. Risk of selection bias is introduced when knowledge of certain patient characteristics, known to be conducive to the success of one particular intervention, is applied together with foreknowledge regarding the allocation of such patients in a specific sequence of interventions. PROBLEM: Selection bias testing has been proposed and recommended on basis of...
CONTEXT: Systematic reviews of clinical trials need to assess the risk of attrition bias as part of its appraisal of the currently available evidence to a particular review question. PROBLEM: Notwithstanding the possible merits of different approaches to estimate the potential intervention outcomes of lost trial participants as the main reason for attrition bias, most remain arbitrary. SUGGESTED SOLUTION: Assuming a worst- and best-case scenario of intervention outcomes provides the certain...
CONTEXT: Systematic reviews aim to assess precision and internal validity of the current clinical evidence. The precision and internal validity of clinical evidence is limited by the risk of biases, one of which is publication bias. Publication bias is created when trials, often with small sample size that have found negative or non-significant results are not being published and thus are not identified during systematic reviews as part of the of current clinical evidence. In that way, publ...
CONTEXT: Quantitative systematic reviews need to consider clinical, methodological and statistical heterogeneity of trials or datasets from trials before combining their results in meta-analyses, as combining results from heterogeneous datasets and/or trials will lead to meaningless results and thus should be avoided. Potential statistical heterogeneity between trials/datasets that have been considered as being clinically/methodologically homogeneous is usually investigated using I2 – t...
Background: Randomised controlled trials (RCT) are highly influential upon medical decisions. Thus RCTs must not distort the truth. One threat to internal trial validity is the correct prediction of future allocations (selection bias). The Berger-Exner test detects such bias but has not been widely utilized in practice. One reason for this non-utilisation may be a lack of information regarding its test accuracy. The objective of this study is to assess the accuracy of the Berger-Exner test...
Hyperglycaemic emergency (HE) is a frequent complication of diabetes mellitus (DM) and one of the commonest causes of hospitalization and death among people living with diabetes and previously unknown diabetes. Mortality from HE is still high in developing countries such as Nigeria; mortality being dependent on co-morbid conditions and precipitating factors. There is no report yet in the literature on the contribution of pre-hospitalization settings to outcome of HE, hence the need for this s...
Cannabis Marijuana has been a term very familiar with the populace for its negative effects and attributes but the good part of this naturally occurring drug is yet to be explored. This article gets to look at the medical benefits attached to cannabis marijuana and why it should be legalized.
Abstract: The study aims at determining the cranial indices of some skulls recovered from cadavers sourced from Southwestern regions of Nigeria, mainly populated by Yoruba ethnic tribe. The cranial indices of 85 human skulls were determined by measuring the maximum cranial length (mcl) and maximum cranial breadth (mcb) using Goniometre fitted with sliding calliper. The cranial index was determined by finding the percentage of the ratio mcb to mcl x100. The skulls were deemed from adult indivi...
Abstract: The study aimed to investigate the relationship between the size of a human skull foramen and the intracranial volume (skull capacity). A total number of 91 human skulls were studied to determine the volume of the foramina and the intracranial volume. The volumes of the foramina were determined by using the formula pie r2h (the geometrical formula of a cone-shaped figure) where ‘r’ is the radius of the effluent aperture, ‘h’ the depth of the foramen and B is a constant. The ...