Assessing the Health Status of a Community
In order to monitor the health of a population it is necessary to record health related events. The earliest systematic records regarding health status of a community were records of births and deaths that were recorded in Europe beginning centuries ago. Around 1592 the parish clerks in London began recording deaths. In 1662 John Graunt, a founding member of the Royal Society of London, summarized the data from these "Bills of Mortality" in a publication entitled "Natural and Political Observations Mentioned in a Following Index, and Made Upon the Bills of Mortality." Graunt analyzed the data extensively and made a number of observations regarding common causes of death, higher death rates in men, seasonal variation in death rates, and the fact that some disease had relatively constant death rates, while others varied considerably. In 1837 England established the General Registrar's Office in order to record births, deaths, and marriages in England and Wales. Dr. William Farr was appointed Chief Statistician, and the data that was collected was used by John Snow and by Edwin Chadwick to explore the determinants of disease by looking at how disease rates differed according to factors such as gender, location, occupation, and social class. Measuring disease frequency and making comparisons among groups of people is essential to identifying the determinants of disease and health.
Massachusetts played a leading role in the evolution of surveillance in the Americas, beginning with registration of births and deaths in 1842. Lemmuel Shattuck headed the Sanitary Commission of Massachusetts, which submitted its "Report of a General Plan for the Promotion of Public and Personal Health" in 1850. In 1874 Massachusetts established a surveillance system that would be described today as "sentinel surveillance" in which a specified group of 168 physicians submitted regular reports on new cases of 14 diseases deemed "dangerous to the public's health." Ten years later the legislature established a list of "reportable diseases," which all physicians were required to report, subject to fine.
Birth certificates and death certificates continue to play a role in health surveillance.
Birth certificates record useful information on live births, but the format and degree of detail varies by state, but all birth certificates contain useful information for health investigations: sex, residence of parent, birth weight, and occurrence of birth defects. Public health officials can analyze data from birth certificates, but birth certificates are generally confidential and not accessible by the general public.
In most US states, death certificates are public records, although some states, e.g., New Hampshire, do not permit public access. In other states access to the record can be limited by the family of the deceased, and in other cases the cause of death is withheld. While the format varies from state to state, death certificates usually indicate :age, sex, race, cause of death, date of death, address, and usual occupation of the deceased. Nevertheless, aggregate data from death certificates is usually available in state or federal offices that provide Vital Statistics. A common problem with death certificates is that there are no strict criteria for classifying the cause of death, so there are many inconsistencies and errors in classification which can introduce misclassification bias into an analysis. For more information about the effects of misclassification of outcomes, which is found in the online learning module on Bias.
The National Death Index (NDI) and Social Security Death Index (SSDI) are two online databases that have mortality data. Data from the SSDI can be accessed by the general public, but one must apply for access to the NDI and pay a fee..
Today there are several other excellent sources of information that were not available when Jimmy Anderson was diagnosed with leukemia in 1972.
Most states now have cancer registries that provide an important means of monitoring cancer rates among the communities in a given state. Massachusetts did not have a cancer registry when the Woburn leukemia cluster was discovered. In fact, the health issues in Woburn were instrumental in the establishment of the Massachusetts Cancer Registry in 1980, and Dr. Richard Clapp, a professor at the Boston University School of Public Health was its first director. In the video below Dr. Clapp discusses the founding of the registry and its importance.
Community Health Reports
Some states provide readily accessible reports and health related data. In Massachusetts MassCHIP provides community-level data to assess health needs, monitor health status indicators, and evaluate health programs. Health care providers, state and federal agencies, universities, community health centers, and local boards of health can all find information relevant to their fields by using MassCHIP. The iFrame below provides access to MassCHIP.
Note that there are prepared reports for many potential health issues. In the column on the far left there is a link for "Cancer," which takes you to a page with links for many specific types of cancer, including leukemia. If you go to the page for leukemia, you will see a number of links, one of which is for "Cities and Towns". This, in turn, brings you to a page that will provide reports on leukemia rates for all of the cities and towns in Massachusetts.
On the next page of this learning module, we will address the calculation and interpretation of "standardized incidence ratios" or SIRs, which provide a way of answering the question of it is unusual to see 12 cases of leukemia in a community like Woburn.
For more information on assessing disease in communities see the online learning module on Surveillance, which includes these specific topics that may be of interest:
- Data Sources for Surveillance and Monitoring the Health Status of the Population
- Massachusetts Cancer Registry
- Environmental Public Health Tracking 101
- Surveillance for Infectious Disease