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Biostatistics involves the application of statistical methods to biological and medical data, including design of experiments and considerations when working with human subjects. This field utilizes mathematical and empirical proofs in medical research, including observational studies, surveys, clinical reports, and experimental studies. Key aspects include comparing treatments concurrently, ensuring random allocation, avoiding biases, and maintaining ethical standards. Methods such as double-blinding and intention-to-treat analysis are essential for reliable results. Proper random allocation methods like coin tossing or computer programs are crucial to avoid biases. Inclusion criteria for subject selection should be carefully defined to ensure study relevance. Overall, biostatistics plays a vital role in providing evidence-based insights in healthcare.
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Biostatistics Carsten Dahl Mørch Fredrik Bajersvej 7 A2-212 Tel: 9635 8757 Mail: cdahl@hst.aau.dk Web: http://www.hst.aau.dk/~cdahl/biostat_9BME/
Biostatistics • Biostatistics is statistics applied to biology • Design of experiments • The limitations when working with human subjects • Non-normality
Proofs • Mathematical proofs: • Emperical proofs: F = m*a
Medical research • Observational studies • Survey • Clinical case report • Experimental studies • Usually comparing treatments • Design
Comparing Treatments • The treatments must be: • Applied concurrently • Treated by the same investigator • Random allocation into treatment groups • Avoid cheating (investigator bias) • Volunteer bias • Intention to treat • Use cross-over design if possible • Double blinded • Ethically solid
Comparing Treatments • The treatments must be: • Applied concurrently • Treated by the same investigator • Random allocation into treatment groups • Avoid cheating (investigator bias) • Volunteer bias • Intention to treat • Use cross-over design if possible • Double blinded • Ethically solid
Concurrent treatment • The wonders of the CT scanner • Patients treated in 1978 for stroke scanned by CT scanner • Patched paired with stroke patients from 1974 (before the scanner)
Concurrent treatment • The wonders of the CT scanner • Patients treated in 1978 for stroke NOT scanned by CT scanner • Patched paired with stroke patients from 1974 (before the scanner)
Comparing Treatments • The treatments must be: • Applied concurrently • Treated by the same investigator • Random allocation into treatment groups • Avoid cheating (investigator bias) • Volunteer bias • Intention to treat • Use cross-over design if possible • Double blinded • Ethically solid
Comparing Treatments • The treatments must be: • Applied concurrently • Treated by the same investigator • Random allocation into treatment groups • Avoid cheating (investigator bias) • Volunteer bias • Intention to treat • Use cross-over design if possible • Double blinded • Ethically solid
Random allocation • Doctors chose for them self if tuberculosis should receive a BCG vaccine or be in the control group
Random allocation • Tuberculosis patients were allocated randomly to receive BCG vaccine or be in the control group
Random allocation • OK: • Toss a coin • Throw dices • Computer programs • http://www.random.org/ • Not OK • Alternation • By date
Comparing Treatments • The treatments must be: • Applied concurrently • Treated by the same investigator • Random allocation into treatment groups • Avoid cheating (investigator bias) • Volunteer bias • Intention to treat • Use cross-over design if possible • Double blinded • Ethically solid
Investigator Bias • Do not allocate by date of arrival: • Patients arriving at even days should be treated, and patients arriving at odd days should act as control.
Comparing Treatments • The treatments must be: • Applied concurrently • Treated by the same investigator • Random allocation into treatment groups • Avoid cheating (investigator bias) • Volunteer bias • Intention to treat • Use cross-over design if possible • Double blinded • Ethically solid
Volunteer Bias • People volunteering for experiments differs form the general population • Obviously more compliant • Volunteers for experiments at AAU?
Volunteer Bias • Salk poliomyelitis with two different designs: • Randomized controls 2nd grades were invited to participate and randomized to either vaccine or saline injection • Observed controls 2nd graters was offered vaccine. 1st and 3rd graders were unvaccinated controls
Volunteer Bias • If vaccine was as ineffective as saline we would expect 200.745*57/100.000 = 114 cases. • In the entire randomized control we would expect 114+114+121 = 350 cases or 46 pr. 100.00 subjects.
Selection of subjects • Low variability makes it easier to detect differences in the treatments • Inclusion and exclusion criterions • Acute bilateral pulmonary tuberculosis • Bacteriologically proved • Between 15 and 30 years • Unsuitable for other treatment • Narrow inclusion criterion makes it difficult to conclude on the general population
Comparing Treatments • The treatments must be: • Applied concurrently • Treated by the same investigator • Random allocation into treatment groups • Avoid cheating (investigator bias) • Volunteer bias • Intention to treat • Use cross-over design if possible • Double blinded • Ethically solid
Intention to treat • Analyzing the data as we had intention to treat the subjects although they may refuse treatment. • All 2nd graders in the observed control study were intended to be vaccinated: (38+43)/(221998+123605)=23 • Conservative estimate
Comparing Treatments • The treatments must be: • Applied concurrently • Treated by the same investigator • Random allocation into treatment groups • Avoid cheating (investigator bias) • Volunteer bias • Intention to treat • Use cross-over design if possible • Double blinded • Ethically solid
Cross-over design • Each subject acts as his/hers own control • Randomization • Carry-over effect of treatment or testing • Treating ‘symptoms’
Comparing Treatments • The treatments must be: • Applied concurrently • Treated by the same investigator • Random allocation into treatment groups • Avoid cheating (investigator bias) • Volunteer bias • Intention to treat • Use cross-over design if possible • Double blinded • Ethically solid
Placebo (response bias) • Any treatment may help • The subject should be blinded to the kind of treatment • Effective treatment should be better than a sham treatment
Placebo • Take the red pill
Double blind studies • When the assessment is made the investigator should be blind to the treatment. • Can all studies be blinded? • Communication between subjects
Comparing Treatments • The treatments must be: • Applied concurrently • Treated by the same investigator • Random allocation into treatment groups • Avoid cheating (investigator bias) • Volunteer bias • Intention to treat • Use cross-over design if possible • Double blinded • Ethically solid
Ethical considerations • The Declaration of Helsinki • Reduce suffering of the subjects • Local ethics comity • Den videnskabsetiske kommité consists of both experts and laymen. • Secures that the rights of the subjects are being followed, especially as to the information given to the subjects.
Ethical considerations • Informed Consent • Subjects must be informed about the nature, purpose, risks etc. in the study. • The subjects should give their consent before being enrolled and have the right to withdraw from the study at any time.
Comparing Treatments • The treatments must be: • Applied concurrently • Treated by the same investigator • Random allocation into treatment groups • Avoid cheating (investigator bias) • Volunteer bias • Intention to treat • Use cross-over design if possible • Double blinded • Ethically solid