3. Gathering and Using Data

OBJECTIVES

  • Recognize the difference between standard clinical practice and preventive medicine.
  • Recall the ways in which, after a disaster, public health measures have a higher priority than caring for individual patients.
  • Describe and apply population evaluation tools such as rates and underlying causes of disease present in a given community affected by a disaster.

Preventive Medicine: A Public Health Mindset

In clinical practice, physicians spend most of their time diagnosing and treating patients one at a time. Most health care is focused on caring for the patient. Preventive medicine, rather than trying to help the individual patient, focuses on the underlying causes of illness in society and employs public health techniques to address these problems at the population level (Box 1).

BOX 1: Characteristics of preventive medicine

  • It is based on public health
  • It deals primarily with the health of groups, not of individuals
  • It uses mathematical data
  • It investigates the underlying causes of disease in the community

The preventive medicine “patient” is considered a group of people, a population, or an entire community with sub-groups within that community. The first step the transition from clinical practice to preventi­ve medicine is to understand your patient. In clinical practice, patients come for consultation with the clinician one by one. Vital signs are determined, and the history, physical examination, and perhaps laboratory tests are used to arrive at a diagnosis and rational treatment plan.

In preventive medicine, the patient is not an individual but a group of people: an entire community. Arriving at an accurate “community health” diagnosis involves taking “vital signs”; however, in this case, those vital signs are mathematical data —rates —of disease within the community and sub-groups within it.

Rates facilitate the comparison between the reality of one community and that of others. They also help assess through time the success of interventions in a given population.

Read the case and consider your answers. Additional case questions appear in later chapters; answers are provided in Chapter 8, Case Resolution.

CASE

After an earthquake, a food poisoning outbreak was detected in a club used as a shelter. An epidemiologist conducted the investigation. On his arrival, Dr. HN was informed that on the previous night all the affected persons had eaten at the club. The investigation focused on the meals served the previous evening. Seventy-five of the 80 persons who had been present were asked about symptoms, including when they were first noticed (date and time of their onset). There were 46 persons with symptoms of gastroenteritis.

  1. Can the situation be considered epidemic?

In all cases, the symptoms, primarily nausea, vomiting, diarrhea, and abdominal pain, had an acute onset. None of the persons had fever. They all recovered spontaneously in a 24- to 30-hour period. Approximately 20% of the persons who had dinner at the club sought medical care. Samples for fecal culture were not obtained.

  1. List the diseases that should be considered in the differential diagnosis when an outbreak of acute gastroenteritis occurs.

Dinner had been prepared simultaneously by several people and had been served in the club yard between 6 p.m. and 11 p.m. The meals had been placed on tables and eaten during a period of several hours. All 75 interviewed persons were asked about the time of onset of symptoms, and the meals and beverages they had. A table was created using these data (see the Appendix in Chapter 10). The exact time of food ingestion could be established in only about half of the cases.