Problem 3: Happy Kids Day Care Center There were 11 children enrolled in the Hap

Question

Problem 3: Happy Kids Day Care Center

There were 11 children enrolled in the Happy Kids Day Care Center from the beginning of Month One until the beginning of Month Five. The 11 children were watched for a total of 4 months. The staff tries to keep good records about when children fall ill from disease X. You are asked to inspect these records and report the following information. The darkened bar indicates the disease is present. For ease of calculations consider one month is equal to 30 days and disease begins on either the 1st or 15th of the month, except for Child #1 who was already ill when record-keeping began.   

A) Calculate the cumulative incidence of disease X from the 1st of Month 1 to the end of Month 2 (over 2 months).   Express this as a percentage.

B) Calculate the period prevalence of disease X from the 1st of Month 2 to the end of Month 3. Express this as a percentage.

C) What is the point prevalence of disease X at the midpoint (15th) of Month 3? Express this as a percentage.

D) Calculate the incidence density at this day care center over the entire study period (from the beginning of the first month to the end of the last month). Express this per 100 child-months (like person-years, but these are children and the disease is developing over months). Show all steps in these calculations.

Explanation / Answer

A)
Cumulative incidence rate = number of persons who newly experience the disease during a specified period of time divided by the (average) total population at risk.

There were 4 new cases reported during 1st of Month 1 to the end of Month 2.

Child 1 was suffering with the disease during 1st of Month 1 to the end of Month 2. So Child 1 was not at risk in this period. So, the total population at risk = 11 - 1 = 10

Cumulative incidence of disease X from the 1st of Month 1 to the end of Month 2 (over 2 months) = 4/10 = 40%

B)

Period Prevalence = Number of cases that occurred in a specified period of time/ Number in the defined population during this period

Number of all cases from the 1st of Month 2 to the end of Month 3 = 6

Period Prevalence = 6/11 = 54.54%

C)

Point Prevalence = Number of existing cases on a specific date/ Number in the defined population on this date

Number of all cases at the midpoint (15th) of Month 3 = 6

Point  Prevalence = 6/11 = 54.54%

D)

Incidence density = Number of new cases / Number of months the population is at risk

Number of new cases during the entire period = 6

Number of months the Child 1 is at risk  = 0 months

Number of months the Child 2 is at risk  = 4 months

Number of months the Child 3 is at risk  = 1.5 months

Number of months the Child 4 is at risk  = 2 months

Number of months the Child 5 is at risk  = 4 months

Number of months the Child 6 is at risk  = 4 months

Number of months the Child 7 is at risk  = 1 month

Number of months the Child 8 is at risk  = 3 months

Number of months the Child 9 is at risk  = 4 months

Number of months the Child 10 is at risk  = 1.5 months

Number of months the Child 11 is at risk  = 0.5 month

Total number of months all childs are at risk = 0 + 4 + 1.5 + 2 + 4 + 4 + 1 + 3 + 4 + 1.5 + 0.5 = 25.5 months

Incidence density = 6 / 25.5 child-months = 23.53 per 100 child-months

Related Questions

Navigate

• Browse (All)
• Browse P
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.