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Efficacy Parameters Major efficacy parameters for most disease are well established but Definite protocol should select those tests and parameters within the limits of resources available to the clinical trial e.g.
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Choosing efficacy parameters 1.
Objective measurements that have been validated and widely accepted
e.g. -
-
B.P. reading Insulin serum Glycosolated haemoglobin Lipid ratios
Direct visualization measure of lesion
e.g. Ulcer – endoscopy arterial blockage - angio tumor size – X Ray or PET 1 YR DCR 2.4.05
and
1.
Reduction in the progress or even reversal of the disease
e..g reduction in the severity of lesions reduction in manifestation of the disease reduction in duration of the disease • • • • •
Improved symptomatology of the patient Improvement of biochemical and lab parameters Improved “Quality of Life” Clinical global evaluation by the Doctor and patient Reduced mortality in those trials where this parameter has relevance. 1 YR DCR 2.4.05
Note
d. e. f. g.
:
The +ve and –ve points of each efficacy parameter incorporated in the protocol must be evaluated against the increase, it will cause to – Time requirements Personal efforts Financial costs Additional complexity especially to the statistical evaluation of the final 1 YR DCR 2.4.05
What are the best parameters? Which parameter to select in a protocol ? Combination of parameters that are practical and make sense to measure should be the best. Parameters of different targets • Objective – Clinical • Subjective – symptomatic • Biochemical • Pathological • Pharmacological C.
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What are the parameter that determine better efficacy over standard treatment? DIRECT a. Time of onset d. Magnitude of effect e. Duration of effect f. Decreased rate of relapse g. Improved quality of life INDIRECT PATIENT COMPLIANCE i. Decreased number of tab/day or dose / day j. Better taste k. Lower cost 1 YR DCR 2.4.05
Factors affecting efficacy a. b. c. d. e. f.
Physical position Relax or exercise After cold or warm bath Patient empty their bladder Prior to meal time Tests at various time of the day (Circardian rhythm) 1 YR DCR 2.4.05
Example disease where parameter to measure is clear Hypertension B.P. reading Here these are many subparameters d. Fall in B.P. of 10 mm or more e. Fall in B.P. to desired level – Normal f. Fall in B.P. over x no. of week g. Maintenance of B.P. over y no. of months h. Maintenance of normal level BP for z no. of months 1 YR DCR 2.4.05
Example of disease when parameter to meet is more complicated e.g. post myocardial infarction – treated to prevent re-infarction and sudden death - Follow up for reinfarction – angiography - No of deaths after 1 year – 2 year
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Efficacy Parameters in Preventive Therapy Prevention of disease : e.g. Vaccine • Prevention of episodes of disease i.e. number, duration or severity of episode is decreased e.g. asthma, epilepsy. C. Prevention of progress of underlying disease. R1 to prevent more serious sequelae of this disease. •
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Preventive Therapy A.
Vaccine – Efficacy Parameter
a. b. c.
Prospective Epidermiology Protocol Prospective & Retrospective protocol Protective level
G.
Preventive of Episode of disease during last 1 week / 1 month how many episode has the patient experienced 0 1 2-5 6-10
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Other Efficacy Parameters A.
• •
“Escape medication” e.g. gastric ulcers, asthma, knowingly incorporated into the protocol. Use Antacid sos or ventoline sos evaluate the frequency of use of escape medication under treatment with the trial during as compared to the baseline or in case of crossover design the placebo period. Decrease in dose of ive therapy 5 years survival in case of cancer therapy 1 YR DCR 2.4.05
Criteria to measure efficacy All or none – Presence of absence criteria 2. Graded criteria applied to 1.
Subjective
a.
as well as b.
Objective symptoms and signs
Global criteria
5. a. b.
Dr. evaluation Patients evaluation 1 YR DCR 2.4.05
Grading Systems for efficacy parameters •
0 Not at all B. 0 Absent 1 Mild 1 Slightly present 2 Moderate 2 Clearly noticeable 3 Markedly 3 Definitely present 4 Severe 4 Continuous & gross 1 YR DCR 2.4.05
0
Absent
1
Rarely present (occurs less than _____times per___) Occasionally present (occurs less than __ times) Often present (occurs __ to __ times per ___) Almost always present (occurs more than __ times per __) e.g. asthma attack
2 3 4
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Extended parameters e.g. asthma No. of attacks per ____ frequency How severe was the attack severity How long did last attack last duration (each of these parameter can also be graded) 1 YR DCR 2.4.05
Type of End points used to measure efficacy 1.
2.
3. 4. 5.
Time for a parameter to improve by a fixed percent (50% or 75% or 100%) Magnitude of improvement at a fixed time i.e. (after 1 week, 1 month) Duration of improvement while on maintenance therapy Time to recurrence of symptoms after treatment is stopped Degree of recurrence of symptoms after treatment is stopped 1 YR DCR 2.4.05
Methods of Evaluating efficacy parameters Compared to baseline or placebo C.
Active drug
E.
Baseline or placebo or comparative drug
A B 9. Incremental change B • Proportionate change B 4. Percent change •
Ratio
:
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:
A minus
:
A-B
:
A-B x
Efficacy parameter with drawing
Eg. Gastric ulcer
End Point 100%
Drug A Drug B
0% of patients With healed Ulcers
= Clinical Symptom = Endoscopy
0 Time 100%
Drug A
0% of patients With ulcer Recurrence
Drug B 0 Time
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= Endoscopy
VISUAL ANALOG SCALES Provide quantitative measures to subjective rating e.g. stress, anxiety, alertness, depression, hunger, itch Pain parameter has been proved to be reliable measured by these scales. Date Time of assessment Score 0 10 No pain Very severe pain
0%
25 %
50 %
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75%
100%
Patient Diaries Date from Patient Diaries give important efficacy information in outpatient evaluation e.g. antiepileptic treatment evaluation anti diarhoea treatment. -
-
The diaries should be designed to make it friendly. Instruction for filling the data should be discussed with the patient and printed on the diary. The diary should be kept with the patient all time i.e. 1 YR DCR 2.4.05
Quality of Life There are a few formal definitions of this term The term “Quality of Life” is used loosely by many We shall only discuss health related Quality of Life
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Schipper et al (1990) “Quality of life represents the functional effect of an illness and its consequent therapy upon a patient as perceived by the patient”
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Four areas contribute to the overall effect
1. Physical and occupational function 2. Psychologic state 3. Social interaction 4. Somatic sensations 1 YR DCR 2.4.05
Components of Quality of life Tests I b. c. d. e. VI. g. h. i. j.
Physical and occupational Capabilities Dysfunction Amount of time at works Work status Psychological Neuropsychologic function (eg. Perceiving, thinking and ing) Emotional state (eg. Anxiety, anger, depression) Personal productivity Intimacy and sexual function 1 YR DCR 2.4.05
I. b. c. d. e. f.
VII. h) i) j)
Socia l Number of s per week / month Quality of social s at home, school, job Quality and quantity of social with friends Interaction at work Recreational activities Somatic s ensations Sleep Pain Bowel movements etc. 1 YR DCR 2.4.05
Is an End point an End point? e.g. Blood pressure measurement
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