Hospital Mortality Rates
| Rate | Numerator | Denominator | Factor |
|---|---|---|---|
| Gross Death Rate | Total deaths (including NB) in a period | Total discharges (including deaths) in same period | x 100 |
| Net Death Rate (Institutional) | Total deaths minus deaths < 48 hours after admission | Total discharges (including deaths) minus deaths < 48 hours | x 100 |
| Newborn Death Rate | Newborn deaths in a period | Newborn discharges (including deaths) in same period | x 100 |
| Fetal Death Rate | Intermediate and late fetal deaths in a period | Total births (live births + intermediate and late fetal deaths) | x 100 |
| Maternal Death Rate | Maternal deaths in a period | Total obstetrical discharges (including deaths) in same period | x 100 |
| Anesthesia Death Rate | Deaths caused by anesthesia in a period | Number of anesthetics administered in same period | x 100 |
| Postoperative Death Rate | Deaths within 10 days of surgery in a period | Total patients operated on in same period | x 100 |
Autopsy Rates
| Rate | Numerator | Denominator | Factor |
|---|---|---|---|
| Gross Autopsy Rate | Total inpatient autopsies in a period | Total inpatient deaths in same period | x 100 |
| Net Autopsy Rate | Total inpatient autopsies in a period | Total inpatient deaths minus unautopsied coroner/ME cases | x 100 |
| Hospital Autopsy Rate (Adjusted) | Hospital autopsies (inpatient + outpatient + former patients) | Deaths of hospital patients whose bodies are available for autopsy | x 100 |
Hospital Infection Rates
| Rate | Numerator | Denominator | Factor |
|---|---|---|---|
| Hospital-Acquired Infection Rate | Total number of hospital-acquired infections in a period | Total discharges (including deaths) in same period | x 100 |
| Postoperative Infection Rate | Number of infections in clean surgical cases | Total number of surgical operations in same period | x 100 |
Bed Occupancy and Utilization
| Measure | Formula |
|---|---|
| Bed Occupancy Rate (% of Occupancy) | (Total inpatient service days in a period / (Total bed count x Number of days in the period)) x 100 |
| Bed Turnover Rate | Total discharges (including deaths) in a period / Average bed count |
| Average Daily Census (ADC) | Total inpatient service days in a period / Number of days in the period |
| Average Length of Stay (ALOS) | Total length of stay (discharge days) / Total discharges (including deaths) |
| Inpatient Service Days | Sum of daily inpatient census counts for a given period (each day a patient is present at census-taking time counts as one inpatient service day) |
Consultation and Cesarean Section Rates
| Rate | Numerator | Denominator | Factor |
|---|---|---|---|
| Consultation Rate | Total consultations provided in a period | Total discharges (including deaths) in same period | x 100 |
| Cesarean Section Rate | Total C-sections performed in a period | Total deliveries (including C-sections) in same period | x 100 |
Vital Statistics
| Rate | Numerator | Denominator | Factor |
|---|---|---|---|
| Crude Birth Rate | Number of live births in a year | Estimated midyear population | x 1,000 |
| Crude Death Rate | Number of deaths in a year | Estimated midyear population | x 1,000 |
| Infant Mortality Rate | Deaths of infants under 1 year in a year | Number of live births in same year | x 1,000 |
| Neonatal Mortality Rate | Deaths of infants under 28 days in a year | Number of live births in same year | x 1,000 |
| Cause-Specific Mortality Rate | Deaths from a specific cause in a year | Estimated midyear population | x 100,000 |
| Case Fatality Rate | Deaths from a specific disease in a period | Number of cases of that disease in same period | x 100 |
Descriptive Statistics Basics
- Mean: Sum of all values divided by the number of values (arithmetic average)
- Median: The middle value when data are arranged in order; not affected by outliers
- Mode: The most frequently occurring value in a dataset
- Range: Difference between the highest and lowest values
- Standard deviation: Measures the spread of data around the mean; a larger value indicates greater variability
- Variance: The square of the standard deviation
Measures of Frequency
- Incidence rate: Number of NEW cases of a disease in a specified time period divided by the population at risk
- Prevalence rate: Number of EXISTING cases (new and old) of a disease at a point in time divided by the population at that time
- Ratio: Comparison of two quantities (A:B) - the numerator is not included in the denominator
- Proportion: A type of ratio where the numerator is included in the denominator
- Rate: A proportion with a time component
Key Exam Tips
- Hospital rates typically use discharges (including deaths) as the denominator, not admissions
- Community/vital statistics rates use population as the denominator
- Know the difference between incidence (new cases) and prevalence (existing cases)
- Average length of stay uses discharge days, not calendar days of the period