Epidemiology module of practical skills for mbbs student

EXERCISE:

In a population of 1000, following are the details of cases of tuberculosis. Calculate incidence, point prevalence (as on 1^st July) and period prevalence for 2001 and comment on it.

Case No	Detected on	Died / Cured on
1	Jan 12, 1999	March 13, 2001
2	Feb 13, 1999	Dec 18, 2000
3	April 29, 1999	Not cured upto 31 Dec 2003
4	Oct 23 1999	Sept 23, 2002
5	Feb 12, 2000	Oct 30, 2001
6	April 1, 2000	Sept 21, 2001
7	June 23, 2000	April 1, 2002
8	Feb 24, 2001	May 23, 2002
9	July 11, 2001	July 12, 2003
10	Aug 15, 2001	April 11, 2002
11	Sept 23, 2001	May 9, 2003
12	Nov 21, 2001	Not cured upto 31 Dec 2003
13	April 12, 2002	July 12, 2003
14	June 13, 2002	Sept 23, 2003
15	Oct 3, 2002	Not cured upto 31 Dec 2003
16	Dec 12, 2002	Dec 23, 2003
17	Dec 16, 2002	Sept 1, 2003
18	Feb 12, 2003	Not cured upto 31 Dec 2003
19	Sept 1, 2003	Not cured upto 31 Dec 2003
20	Oct 11, 2003	Not cured upto 31 Dec 2003

4. 
   MEASUREMENTS OF MORTALITY
   
   1. 
      Crude Death Rate
      

It is defined as “the number of deaths (from all causes) per 1000 estimated mid year population in one year, in a defined geographical area.

No. of deaths during the year

Crude Death Rate = ------------------------------------x 1000

Mid year population

2. 
   Specific Death Rates: can be specific to age, sex, occupation, diseases, etc.
   

Disease Specific Mortality:

No. of deaths from specific disease

during a calendar year

Disease Specific = ------------------------------------------------ X 1000

Mortality Rate Mid year population

Example: In a village with population of 5000 there are 5 deaths due to tuberculosis occurred in a year. Death rate due to tuberculosis would be 1 per 1000.

Child Mortality

Still Birth Ratio: Defined as “ Death of foetuses weighing 1000 gm (this is equivalent to 28 weeks of gestations) or more occurring during one year in every 1000 live births.

Foetal deaths weighing 1000gm or more at birth

Still Birth=------------------------------------------------------------- X 1000

Ratio Total no of live births

Still Birth Rate: Still Birth Rate is defined as number of deaths of foetuses weighing 1000gm or more occurring during 1 year per 1000 total births (live + still births).

Still Foetal death weighing 1000gm or more at birth

Birth = --------------------------------------------------------------- X 1000

Rate Total (live + still) births weighing 1000gm or more at birth

Neonatal Mortality Rate (NMR): NMR is defined as the number of neonatal deaths under 28 days of age in a given year per 1000 live births in that year

No of death of children under 28 days of age in a year

NMR=------------------------------------------------------------------- x1000

Total live births in the same year

Post-neonatal Mortality Rate: It is defined as the ratio of post neonatal deaths (28 days to under one year) in a given year to the total number of live births in the same year, usually expressed as a rate per 1000.

No. of deaths of children between 28 days

and one year of age in a given year

PNMR = ------------------------------------------------------- X 1000

Total live births in the same year