Evidence Based Medicine
Critical Appraisal
Which of the following is NOT a benefit of systematic review:
Answer:
Systematic review is not immune to bias. Ensuring all papers have an equal chance of being in the systematic review (e.g. including unpublished studies, studies in other languages etc.) minimises bias.Systematic Review
Evidence Based Medicine / Critical Appraisal
Last Updated: 21st April 2019
A systematic review (SR) is a formalised and stringent process of searching and identifying, critically evaluating, and selecting for inclusion based on predefined quality criteria, all relevant studies (both published and unpublished) surrounding a particular clinical question. Systematic reviews are the gold-standard source of research evidence in the hierarchy of research evidence.
Systematic review achieves:
- refinement and reduction - large quantities of information are refined and reduced to a manageable size
- efficiency - SR is quicker and less costly to perform than a new study, it can prevent others from embarking on an unnecessary study and can shorten time between medical developments and their implementation
- generalisability and consistency - results can often be generalised to a wider population in a broader setting than would be possible from a single study, consistencies in the results from different studies can be assessed and inconsistencies determined
- reliability - SR aims to reduce errors and so tends to improve the reliability and accuracy of recommendations
- power and precision (meta-analysis has greater power to detect effects of interest and provides more precise estimates than a single study)
Meta-Analysis
A meta-analysis the quantitative assessment of a systematic review. It involves combining the results of independent studies with common features to produce a more powerful overall estimate of effect. A meta-analysis can provide conclusive evidence for or against an intervention, even when individual studies are inconclusive.
In meta-analysis of RCTs, the outcome data from each trial are usually illustrated as a series of odd ratios with their confidence intervals on a graph known as a forest plot.
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- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
