Disease pattern analysis seeks to determine the location, time, people affected, causes, spread and results (such as mortality) of disease. Pattern analysis works with data gathered and recorded systematically, so that information from one person, town, country or region may be easily, and reliably, compared with another. Systematic medical coding, such as that enabled by the most recent International Statistical Classification of Diseases and Related Health Problems (ICD-10), generally meets the need of disease pattern analysis for reliable, systematic data.

Disease Pattern Analysis

Disease pattern analysis arises out of epidemiology, a discipline that, in pertinent part, studies the frequencies and patterns of disease, as well as their causes. A proper analysis requires observation, recordation and description, all of which is greatly aided by the systematic classification and recording of disease provided by medical coding.

Brief History of Epidemiology

Hippocrates (460 BC - 370 BC) is credited with inventing epidemiology with his theories on environmental factors and disease. Rudimentary statistical evidence was collected as early as the mid-17th century when John Graunt used mortality rolls to create disease trends. Slightly more advanced statistics were used 200 years later when Dr. John Snow, the father of modern epidemiology, compared death rates to determine the cause of a cholera epidemic. Sophisticated statistical methods did not emerge in the field until the early 20th century.

Epidemiology Today

Modern epidemiology can take a variety of forms. Ecological studies compare data sets of entire populations and may be geographical (comparing communities), time trends (comparing changes over time), migrants (distinguishing genetic from environmental causes) and occupational/social-economic (considering the unique factors of a group).

Longitudinal studies observe associations between causes of disease and their outcomes over time. With cross sectional studies, epidemiologists use data sets to measure factors and causes of a particular health issue in a certain population over a short period (or simply a point) of time.

Without doubt, each of these methods requires reliable, systematic data in order to produce valid disease pattern analysis. An international system of medical coding, where physicians, nurses, public health professionals and others all use the same methods and terms to designate the various factors and outcomes of disease, has enabled the production of meaningful analysis of disease, morbidity and mortality.

Medical Coding

Medical coding employs a disease classification system so that occurrence and distribution can be easily quantified, and thereby, used in statistical analysis. The universally accepted system, the ICD, has been employed by the international community, in a variety of iterations for decades. Properly used, medical coding provides the foundation for thorough disease pattern analysis.

Brief History of Medical Coding

Sauvages, in the 18th century, is widely credited with creating the first medical coding system with Nosologia Methodica. An international system of classification was not adopted until 1855 when the International Statistical Congress first did so. By 1893, the system was termed the International List of Causes of Death. In 1938, the Fifth International Conference for the Revision of the International List of Causes of Death adopted a version that met the needs of the variety of involved groups, including health insurers, military medical services, hospitals and health administrators.

By the sixth revision in 1948, titled International Statistical Classification of Diseases, Injuries and Causes of Death, the conferees agreed on a comprehensive list of mortality and morbidity, international rules for classification and an index with coded diagnostic terms. In 1975, the ninth version (ICD-9) incorporated the now-familiar three-digit categories, four-digit subcategories and optional five-digit subdivisions, as well as the optional method of classifying diagnoses for medical care providers.

Medical Coding Today

For the tenth revision, conferees intended to create a stable yet flexible classification system that would not require frequent revision. The ICD-10, finalized in the mid-1990's, introduced an alphanumeric coding scheme and the "family of classifications" concept was further incorporated.

In the United States, the ICD-9 and ICD-10 have been modified into the ICD-9-CM and ICD-10-CM, to assign codes for inpatient, outpatient and doctor office diagnoses and procedures, to capture greater morbidity detail and to better assure clinical accuracy and usefulness.

Some specific advances in ICD-10-CM include expanded injury codes, combination diagnosis/symptom codes and greater specificity in code assignment.

ICD-10 in Disease Pattern Analysis

Two prominent studies, conducted by Watzlaf, et al and a joint AHA/AHIMA project respectively, revealed that the ICD-10-CM provides greater specificity, and gathers data about more public health diseases, than the ICD-9-CM.

Both studies demonstrated that ICD-10-CM more fully captured data relating to reportable diseases. Their analyses revealed that ICD-10-CM, with its increase in codes, categories, explicit terms and specificity, captures more data related to mortality than the ICD-9-CM.

For example, ICD-10-CM was found to have fully captured disease-related data of angina, atherosclerosis, malignant lung neoplasm, malignant breast neoplasm, Alzheimer's disease, diabetes mellitus and influenza. ICD-9-CM failed to fully capture data on any of these leading causes of death.