Tiêu đề 2. MEASUREMENT OF OUTCOMES IN PHARMACO-EPIDEMIOLOGY.pdf ✅

PHARMD GURU Page 1 INTRODUCTION:  Epidemiology is about identifying association between exposure and outcomes.  To identify any associations, exposure and outcomes must first be measured in a quantitative manner.  In treatments & health care programs, outcomes are the results of treatment (or) care, which includes both positive and negative results.  Outcome indicator: measures performance of function process and outcomes over a period of time.  Outcome measurement: It is defined as the systematic quantitative analysis of the outcome indicator at a point of time.  These measures are used to find out whether the goal of the patient, are identified and achieved. measurement of outcomes can be done by two approaches: 1) Statistical Methods 2) Drug use measures. 1) STATISTICAL METHODS: a) Prevalence b) Incidence  Cumulative incidence  Incidence rate (or) Incidence density MEASUREMENT OF OUTCOMES IN PHARMACO- EPIDEMIOLOGY STATISTICAL METHODS PREVALENCE INCIDENCE CUMULATIVE INCIDENCE INCIDENCE RATE (OR) INCIDENCE DENSITY
PHARMD GURU Page 2 a) PREVALENCE:  It is the proportion of people affected with a disease (or) exposure to a particular drug in a population at a "specific point (or) period of time".  It is usually determined by surveying the population of interest.  Prevalence varies between 0-1; it can be expressed as percentage.  It is a census type of measure, indicating how frequently a disease is at a period of time. USES:  Estimate the magnitude of health (or) disease problem in the community.  To identify the potential high risk population community.  It is especially useful for administrative and planning purpose.  Mathematically, Prevalence = A/B A = no. of population with disease at a given time. B = Total no. of population at a given time. Ex: If there are 1000 patients with epilepsy in a district of 10, 00,000 population. Then prevalence of epilepsy = 1000/10, 00,000 = 0.001% b) INCIDENCE: Definition: It is a measure of the risk of developing some "new condition" within a specific period of time. In the case of descriptive studies two measurements of incidents are commonly used: 1) Cumulative incidence 2) Incidence density or incidence rate CUMULATIVE INCIDENCE:  It is a number of new cases within a specific period of time, divided by the size of population initially at risk.  It is used for the measure of the risk of disease or probably probability of developing the disease during specified period.  Normally it is measured with an Inception cohort i.e. a large group of population is observed over a period of time, and the number of cases or outcomes is measured.
PHARMD GURU Page 3 No. of new cases of disease (or) injury during specified period Size of population at start of period Example: If a population initially contains 1000 non disease persons & 28 develop a condition over two years of observation, the incidence proportion is 28 cases per 1,000 persons. INCIDENCE RATE:  It is the number of new cases per population at risk in a given period of time.  It describes the probability of a new case occurring during a given time interval (or) how quickly disease occurs in a population.  It is a measurement combining the number of persons and their time contribution (years, months or weeks) in a study. Number of new cases of disease (or) injury during specified period. Total time each person was observed (totaled for all persons) RELATIONSHIP BETWEEN PREVALENCE AND INCIDENCE: P = I x D D = Duration. It shows, longer the duration of the disease, greater the prevalence. 2) DRUG USE MEASURES: 1) Monetary units. 2) Number of prescriptions. 3) Units of drugs dispensed. 4) Defined daily doses (DDD). 5) Prescribe daily doses (PDD). 6) Medical adherence measurement. 1) MONETARY UNITS:  Drug use has been measured in monetary units to quantify the amounts being consumed by population.  It can indicate the burden on society from drug use. IR = C.I =
PHARMD GURU Page 4  Monetary units are convenient and can be converted to a common unit, which then allows for comparison.  The disadvantage is quantifies of drug actually consumed, are not known and prices may vary widely. 2) NUMBER OF PRESCRIPTIONS:  It has been used in research, due to the availability and ease.  Prescription number analysis is used to get rough estimates like percentage of analgesic drugs, oral contraceptives or antibiotics used by the population,  It helps to give comparatively good estimates of number of people expose you to a certain drug. These types of studies also help to find whether there is increase in the number of prescriptions during certain periods. 3) UNITS OF DRUG DISPENSED:  Units of drugs represent measures like number of capsules (or) tablets (or) tablets (or) doses of vaccines.  It is easy to obtain and can be used to compare usage trends within population.  Helps to analyze drug use trend in various countries, states (or) territories of country.  Helps to compare the hypothesis generated related to drug use, like overuse (or) under use.  It has limitations like units of drugs dispensed need not always reflect the actual number of drugs used by the population. people may not use certain dispensed medicines for various reasons.  Hence, difficult to determine the actual number of patients exposed to the drug. 4) DEFINED DAILY DOSES (DDD):  According to WHO, the DDD is the assumed average maintenance dose per day for a drug for its main indications in adults.  It is normally expressed as DDD/1000 Patients/day (or) DDD/100 bed/day. Item used amount of drug per item Drug usage = DDD