3 Groups about Measures of Morbidity

Physician - Epidemiologist / Khaled M. AlmazAssistant lecturer, Community Medicine Department,

Aswan University hospital, Aswan, EgyptMaster Degree in Public Health , October 2011Master Degree in Internal Medicine , April 2015

Measures of Morbidity1.Incidence2.Prevalence3.Disability

Identify pattern of Food IntakeIndirect Methods for Nutrition

AssessmentNutrition Assessment at the National

LevelNational Food Consumption & Food Balance Sheet.

Vital statistics Assessment of the Ecological factors.

الحيويه = Vital statistics االحصاءاتالمباشرة غير الطرق

بعض االحصاءات الدولتوجد لدى بعض • التي تستعمل كمؤشر عن الكفاية الحيويه

التغذوية..:-وهي تشمل •

االعمار, الوفيات وسجالت1.

واالصابة باالمراض,2.

.االمراضوأسباب 3.

Vital statisticsIndirect indicators : for the nutritional status of the community :1. Mortality rate : - Infant mortality, neonatal mortality, still birth, per-natal mortality rates. - Child ( = under five mortality rates ).2. Morbidity statistics : Life expectancy (Survival Rate) (Disease

Burden).3. Morbidity statistics : Incidence rate - Prevalence rate.

Classification for estimating Mortality and Disability

Deaths were classified using a tree structure, in which the first level of disaggregation comprises three broad cause categories of diseases :-

1. Group I: communicable diseases, perinatal, and nutritional conditions;

2. Group II: non-communicable diseases;3. Group III: injuries.

Morbidity statistics to assess the frequency of the

disease

Incidence rate.

Prevalence rate.

Disease burden.

Morbidity statistics : Incidence rate - Prevalence rate

Incidence rate : new cases of Nutritional Diseases ( Over Nutrition / or / Under-Nutrition = Deficiency ).

Prevalence rate : new + old : all cases of Nutritional Diseases ( Over Nutrition / or / Under-Nutrition = Deficiency ).

(service statistics derived from hospitals) e.g. 1. protein energy malnutrition among (marasmus- kwashiorkor), 2. Rickets among hospital attendants.3. iron deficiency anemia among hospital attendants.4. keratomalacia among hospital attendants.

Basic Formulas for 2 x 2 Tables

2 x 2 Table for

Case-Control or

Cohort

Cumulative Incidence Data

Exposure Status Outcome Exposed Unexposed

Presentcases m1

Absentcontrol m0

n1 n0 t a+b+c+d=t

b a

d c

2 x 2 Contingency table for Calculation of Measures of Association

  Outcome Exposur

e Present Absent TOTAL

Present a b a+b

Absent c d c+d

TOTAL a+c b+d a+b+c+d

Note: “Exposure” is a broad term that represents any factor that may be related to an outcome.

Measures of Effect ,, Cohort study

1. Absolute risk = Incidence.2. Cumulative Incidence Relative Risk (CIR) , Relative risk (risk

ratio or rate ratio).3. Risk Difference (RD).4. Attributable Risk.5. Attributable proportion (attributable risk %).6. Population attributable risk.7. Incidence density = Person-time analysis.

Cohort , Incidence ,

Relative Risk (Ratio)

Measures of Effect ,, Cohort Study

Incidence Density relative risk (IDRR)Incidence Density Ratio

Incidence Density Data in exposed group= -------------------------------------------------

Incidence Density Data in non exposed group

Incidence Density Data in exposed group new cases of disease that of interest (that researcher was need this disease

not another disease) in exposed group= -----------------------------------------------------------------------------

summation of life time of all people in exposed group (until he died , before he diseased , until the cohort study is ended) in exposed group

*** new cases in exposed group mostly and 99 % is more than new cases in non- exposed group…1. If person number 4 diseased in 10th month >>> so his life time is 9

months…2. If person number 8 died in 6th month >> so his life time is 6 months…3. If person number 2 still healthy or got diseased not of interest for cohort

study depend upon researcher interest >> so his life time is for example 20 months >> if the cohort study is ended at 20th month…

Incidence Density Data in non exposed group new cases of disease that of interest (that researcher was need this disease

not another disease) in non exposed group= -----------------------------------------------------------------------------

summation of life time of all people in exposed group (until he died , before he diseased , until the cohort study is ended) in non exposed group

*** new cases in non-exposed group mostly and 99 % is less than new cases in exposed group…1. If person number 4 diseased in 10th month >>> so his life time is 9

months…2. If person number 8 died in 6th month >> so his life time is 6 months…3. If person number 2 still healthy or got diseased not of interest for cohort study

depend upon researcher interest >> so his life time is for example 20 months >> if the cohort study is ended at 20th month…

2 x 2 Table for Incidence Density Data

Exposure Status Outcome Exposed group Unexposed group

Present cases

(Disease) m1

Person-time n1 n0 t

B a

2 x 2 Table for Incidence Density Data

A = number of persons who developed the disease in the exposed group.b = number of persons who developed the disease in the unexposed

group.n1 = the amount of person-time of follow-up for the exposed group.n0 = amount of person-time of follow-up for the unexposed group.m1 = total number of persons with the outcome.t = total amount of person-time.

Incidence Density relative risk (IDRR)In the Numerator البسط : all new cases

All new Cases = new cases in exposed group + new cases in non-exposed group.

Incidence Density Data : only diseased cases , patients. المرض لحدوث يكفي الوقت من المرضي : كم لم بين والذين تعرضوا الذين

الخطورة يتعرضوا ….لعوامل

Case Control , Prevalence

Odd`s Ratio

Measures of Effect ,, Case Control study

Odd`s Ratio (OR)

** Incidence : Causation of disease is related to factors present before disease of incidence.** Prevalence : represent Survival.

Measures of Effect ,, Case Control

Odds Ratio = a*d / b*c

The odds Ratio for a case-control study is the odds of the disease in the exposed group relative to the odds of the disease in the unexposed group.

A : diseased + exposed

B : diseased + non-exposed

C: Non-diseased + exposed

D: Non-diseased + non-exposed

OR : a/c ad

-------- = ----------

b/d bc

As it is ratio (odd`s ratio) so we say a / c but not a / a+c as in risk (relative risk)

b / d but not b / b+d as in risk (relative risk)

OR = odd`s in exposed / odd`s in non-exposed (unexposed).

Prevalence

Prevalence rate can be calculated from :Descriptive Studies :

1. Cross-Sectional study.

2. Longitudinal Multi Cross Sectional Study.

3. Ecological Correlational study : measure Frequency & its correlation with

incidence & prevalence.

Prevalence—definition

Number of cases of disease at a specific time Population exposed at that time

• Definition: Proportion of a population affected by a disease at a specific time.

• Expressed as a percentage

Prevalence Rate during a specified period

of time…

If no time specified >> so

Prevalence Proportion

Prevalence ,,,, TypesPoint prevalence : Proportion of a population affected by

a disease at a point in time

Period prevalence : Proportion of a population affected by a disease during a certain period of time– How many people have had the disease at any time during a

certain period?

Screening Test Study designPrevalence

No Incidence estimation ( in screening test )

Dx Test: Case - Control Sampling

Disease +Sampled Separately

Disease –Sampled Separately

Test +a

True Positivesb

False Positives

Test -c

False Negativesd

True Negatives

Totala + c

Total With Diseaseb + d

Total WithoutDisease

Sensitivity = a/(a + c)Specificity = d/(b + d)

Dx Test: Cross - Sectional Sampling

Prevalence = (a + c)/ NPositive Predictive Value = a/(a + b)Negative Predictive Value = d/(c + d)

Disease + Disease - Total

Test + aTrue Positives

bFalse Positives

a + bTotal Positives

Test - cFalse Negatives

dTrue Negatives

c + dTotal Negatives

Total a + cTotal With Disease

b + dTotal Without

Disease

a + b + c + dTotal N

Evaluation of a screening program

¨Reliability (Repeatability)¨Feasibility¨Validity (Accuracy)¨Performance (Practability)¨Effectiveness¨Yield of the Screening Test

EffectivenessOutcome measures:

1. Morbidity2. Disability3. Mortality

Disability Measures

Life expectancy (Survival Rate)

---------------Morbidity statistics :

To assess the frequency of the diseaseDisease Burden

( years of potential life lost )DALYs : Disability-adjusted life year QALYs : Quality-adjusted life years

Types of Disease Burden

DALYsQALYsHALE

Indicators of HealthDisability Indicators: Sullivan's index , HALE (Health Adjusted Life Expectancy) , DALY (Disability Adjusted Life Year).

===============Sullivan's index is a expectation of life free from disability.HALE is the equivalent number of years in full health that a newborn can

expected to live based on the current rates of ill health and mortality. DALY expresses the years of life lost to premature death and years lived

with disability adjusted for the severity of disability.

Summary measures of population health

Summary measures of population health are measures that combine information on :-

Mortality and non-fatal health outcomes to represent the health of a particular population

As a single number. Over the past 30 years or so, several indicators have been developed

To adjust mortality to reflect the impact of morbidity or disability. These measures fall into

Two basic categories, health expectancies and health gaps (1-3).

Health ExpectanciesHealth expectancies measure years of life gained or years of improved quality of life. In this group of measures, among others, Following Measures are classified:1. Active life expectancy (ALE),2. Disability-free life expectancy (DFLE),3. Disability-adjusted life expectancy (DALE),4. Healthy adjusted life expectancy (HALE),5. Quality adjusted life expectancy (QALE).

Health GapsHealth gaps measure lost years of full health in comparison with some ‘ideal’ health status or accepted standard. In this group of measures among others,Following Measures (indicators) are classified:1. Potential years of life lost (PYLL),2. Healthy years of life lost (HYLL),3. Quality adjusted life years (QALY),4. Disability adjusted life years (DALY).

Both approaches use Time and multiply number of years lived (or, not lived in case of premature death) by the “quality” of those years. The process of adjustment of the years of healthy life lived is called “quality adjustment” (expressed as QALYs)… The process of adjustment of the years of healthy life lost is called “disability adjustment” (expressed as DALYs)…

It means that QALYs represent a gain which should be maximized,

DALYs represent a loss which should be minimized. In the QALY approach the quality is weighted (sometimes called

“utility”, as it is the case of cost-utility analyses) on a Scale

from 1 indicating perfect health and the highest quality of life, to 0 indicating no quality of life and is synonymous to death.

In the DALY approach the Scale goes in opposite way: a Disability weighted zero indicates perfect health (no disability), and weighted 1 indicates death.

The Disability weighting is the most difficult and controversial part of the DALY approach .

QALYs

What are QALYs?Combines length and quality of life into single unitWeights used to adjust survival data• Involves valuing health states on a cardinal (interval or ratio)

scale with maximum value of 1 (perfect health) and value of 0 equal to death

Used to weight life yearsQALY = (length of life) x (QoL)

QALYs

QALYs

Calculating QALYsPrognosis without treatment

(0.7x1( + )0.6 2x( + )0.4 1x( + )0.3 1x( + )0.2 1x( + )0.1 2x = )3.0

Prognosis with treatment(0.5x1( + )0.6 1x( + )0.7 1x( + )0.8 1x( + )0.9 4x = )6.2

Total gain in QALYs6.2 – 3.0 = 3.2

Estimating QALYs using an index measure

1. EQ-5D (EuroQol)2. Health Utilities Index (HUI II and HUI III)3. Quality of Well-Being Scale (QWB)4. 15D5. SF-6D (derived from SF-36)

DALYs

DALYs

Calculation of DALYsDisability-Adjusted Life Year

(DALY) conceptThe DALY measure is the sum of both dimensions / components just described :-

The Sum of the YLLs and the YLDs (4,10,11,15-19) :

DALY = YLL + YLDDALY = disability adjusted life yearsYLL = years of life lost due to premature deathYLD = years lost due to disability

Calculating DALYs.At the end the YLLs and the YLDs are summed up according to Equation 4.

The sum of the YLLs and the YLDs (4,10,11,15-19) :

DALY = YLL + YLDFor the woman from Example 8 the DALYs are calculated as follows:DALY = 33.99 + 10.50 = 44.49The burden of disease in this case in terms of DALYs is 44.49 years.

LY – Life YearsLife years can be obtained from life tables

• Average life expectancy• For example: Life expectancy at birth by health and local

authorities in the United Kingdom 1991-1993 to 2002-2004, including revised results for England and Wales 1991-1993 to 2000-2002 accessed via http://www.statistics.gov.uk/statbase/Product.asp?vlnk=8841

Some evaluations require information about survival linked to the intervention

Statistics1. Survival Analysis Statistical Tests2. Hospital Statistics

1 - Survival Analysis Statistical Tests

Survival rate is a time , usually estimated as months , but it can be estimated by days or years.

2– Hospital Statisticsالخدمات مراكز في الطبي االحصاء

الصحية

Used in :-

1. Health Care Administration (Hospital Administration)

2. Medical Statistics

Types of Hospital Statistics Vital statistics :

Births & Deaths Patients statistics

Demographic dataAdministrative data : Stay , mode of Treatment , Discharge Utilization statistics

Bed use & Patient Movement StreamNumber of patients , Visits , lab & radiology InvestigationsBed use : Occupancy , Turnover , Stay

Quality Administration

Quality Assurance of Medical Practice

QUALITY OF HEALTH CARE

What is Quality?

“The quality of technical care consists in the application of medical

science and technology in a manner that maximizes its benefit to

health without correspondingly increasing risks. The most

comprehensive and perhaps the simplest definition of quality is that

used by advocates of Total Quality Management: “Do the right thing,

right, the first time.”

Components of Quality

1. Effectiveness

2. Efficiency

3. Technical ~2ornpeence

4. Safety

S. Accessibility

6. Interpersonal Relations

7. Continuity

8. Amenities

Effectiveness: doing "right" things, i.e. setting right

targets to achieve an overall goal

Efficiency: doing things in the most economical

way (good input to output ratio)

Outcomes in Economic Evaluation

Economic evaluation involves comparative analysis of two or more interventions in terms of both costs AND benefits

Outcome measurement therefore importantWhat sorts of outcomes do we want?

Cost EffectivenessCost-effectiveness analysis (CEA) is a form of Economic Analysis that compares the Relative Costs and Outcomes (Effects) of different courses of action. Cost-effectiveness analysis is distinct from cost–benefit analysis, which assigns a monetary value to the Measure of Effect.

The most commonly used Outcome Measure is Quality-Adjusted Life Years (QALY).A special case of CEA is Cost–Utility Analysis , where the

Measure of Effect in terms of years of full health lived, using a measure :

1. Quality-Adjusted Life Years. 2. Disability-Adjusted Life Years.

Cost-Effectiveness is typically expressed as an incremental cost-effectiveness ratio (ICER), the ratio of change in costs to the change in effects.

A complete compilation of Cost-Utility Analyses in the peer reviewed medical literature is available from the Cost-Effectiveness Analysis Registry website.

التكلفة فعالية CEAتحليل التكاليف بين المقارنة أساس على يقوم والذي االقتصادي، التحليل أشكال من

. ) العمل ) خطط من أكثر أو باثنتين الخاصة الصلة ذات التأثيرات النتائج وبين يعين والذي والفائدة، التكلفة تحليل عن التكلفة فعالية تحليل مفهوم ويختلف

. المتّبع التأثير مقياس على النقدية القيمة ما الحاالت وعادةً في الصحية، الخدمات مجال في التكلفة فعالية تحليل يُستخدم

. يتم عام، وبشكل الصحي الوضع على التأثيرات معرفة فيها يصعب عن التي التعبيرالمكاسب إلى المقام فيها يرمز الناتجة النسبة إن حيث من التكلفة فعالية تحليل

سنوات ) المبكرة، الوالدة حاالت تفادي الحياة، سنوات القياس عن الناتجة الصحية) بالرؤية الصحية التمتع بالمكاسب المرتبطة التكلفة البسط .ويمثل

الجودة ويعد حيث من الحياة سنوات النتيجة.. QALYمقياس مقياس هو. اإلطار هذا في شيوعًا أكثر بشكل المستخدم

القول يمكن الوقت، نفس لتحليل وفي مماثل التكلفة فائدة تحليل إن . التكلفة فعالية

Cost Efficiency (Cost Optimality)In the context of Parallel Computer Algorithms, refers to a

Measure of how Effectively Parallel Computing can be used to solve a particular problem.

A Parallel Algorithm is considered Cost Efficient if its Asymptotic Running Time multiplied by the number of processing units involved in the computation is comparable to the Running Time of the best sequential Algorithm.

For example, an Algorithm that can be solved in time using the best known sequential Algorithm and in a Parallel Computer with processors will be considered Cost Efficient.

) المثالية ) التكلفة أو الكفاءة أو الفعالية كلفةالمتوازية • الحو�اسيب خوارزميات مجال� فيمدى • قياس إلى المتوازية فعاليةيشير مشكلة الحوسبة حل أجل من

معينة. الوقت • كان إذا التكلفة حيث من فعالة أنها متوازية خو�ارزمية تعتبر

المشاركة المعالجة وحدات من عدد في مض�روبا للتشغيل المقارب. تسلسلية خو�ارزمية أفضل تشغيل مدة تعادل الحساب في

،المثال سبيل المدة على في حلها يمكن التي للخوارزمية سينظرO(n) معروفة متسلسلة خوارزمية أفضل كمبيوتر و باستخدام في

معالجات مع التكلفة O(p) mبالتوازي حيث من ...كفعالة

Cost–Benefit Analysis (CBA) = Benefit–Cost Analysis (BCA)

1. It is a systematic approach to estimating the strengths and weaknesses of alternatives (for example in transactions, activities, functional business requirements);

2. It is used to determine options that provide the best approach to achieve benefits while preserving savings.

3. The CBA is also defined as a systematic process for calculating and comparing benefits and costs of a decision, policy (with particular regard to government policy) or (in general) project.

والفائدة التكلفة CBA / BCAتحليلسياسة • أو قرار أو مشروع وتكاليف فوائد حساب خاللها من يمكن منهجية عملية عن عبارة

. )" بينها )" والمقارنة ما المشروع حكومية: والفائدة التكلفة لتحليل غرضان وهناك

1.) / ( / ، الجدوى التبرير سليًما اتخاذه تم الذي القرار االستثمار كان إذا ما تحديد

2. . هذه وتُبنى المشروعات بين المقارنة في عليه االعتماد يمكن أساس توفيرفي خيار لكل المتوقعة اإلجمالية التكلفة بين المقارنة أساس على العملية

تفوق الفوائد كانت إذا ما لمعرفة المتوقعة، اإلجمالية الفوائد مقابل. كمية وبأي التكاليف،

Study Designs

used in

Outcomes Research

in

Quality Assurance of Medical Practice

1. Randomized control trials

2. Cross-sectional studies

3. cohort studies

4. Meta-analysis

5. Systematic reviews

SPSS Program

Minitab Program

( used Mainly in Quality Administration )

• Disability measures

• Related to survival analysis :• Demography & population problem• Quality of health care services