Evidence Based Medicine
Statistics
Regarding epidemiology, which of the following statements is CORRECT:
Answer:
The incidence of a disease is the number of new cases of a condition over a given time period, given as a percentage of the population. The point prevalence of a disease is the existing number of cases of a condition at a single point in time, given as a percentage of the population. The mortality rate is a type of incidence rate defined as the total number of deaths attributed to a disease in a given time period in a population. With chronic diseases, the incidence will be lower than the prevalence. With short-term illnesses e.g. the common cold, the incidence will be greater than the prevalence. Cross-sectional studies can be used to estimate the prevalence of disease in a population.Epidemiological Data
Evidence Based Medicine / Statistics
Last Updated: 21st March 2019
Epidemiology is the scientific study of the distribution, causes and control of diseases in the population.
The incidence of a disease is the number of new cases of a condition over a given time period, given as a percentage of the population.
The point prevalence of a disease is the existing number of cases of a condition at a single point in time, given as a percentage of the population. Period prevalence of a disease can be assessed using repeated cross-sectional studies to find out the proportion of a population that has the disease over a given time period.
With chronic diseases, the incidence will be lower than the prevalence. With short-term illnesses e.g. the common cold, the incidence will be greater than the prevalence.
The mortality rate is a type of incidence rate defined as the total number of deaths attributed to a disease in a given time period in a population.
The morbidity rate is the rate of occurrence of new non-fatal cases of the disease in a defined population at risk over a given time period.
The median survival denotes how long patients survive with a disease. It is the time period at which 50% of the patients are expected to be alive.
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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 |
