Systems Therapeutics and Disease Categories

Reposted from Medium 2023

“Without context and purpose, information is mere data.”

Clement Mok in Designing Business


Systems therapeutics has previously been described in detail, illustrating how pharmacologic processes and pathophysiologic processes interact to produce clinical therapeutic response. Various disease categories have classically been used to categorize or describe different diseases, but these have generally not provided comprehensive and systematic descriptions related to disease development and progression. The objective of this report is to provide examples of disease categories and explore where to place these within the systems therapeutics scheme.

Systems Therapeutics

Systems therapeutics defines where pharmacologic processes and pathophysiologic processes interact to produce a clinical therapeutic response. A systems therapeutics diagram has been described to illustrate these interactions, consisting of parallel pharmacologic and pathophysiologic processes. While systems therapeutics has been described in detail (1), what has not been discussed includes how disease categories might be placed within this scheme. A related report has showed how disease modifiers could be placed within the systems therapeutics scheme (2); disease modifiers are factors which can potentially influence clinical disease development and progression, such as sex and age, and different risk factors and aggravating factors. The objective of this report is to review different disease categories and determine where these can be placed within the pathophysiologic process part of the systems therapeutics diagram.

Disease Categories

Diseases have classically been categorized or described in different ways. These range from being organ system based to how common vs. rare the diseases are. While these disease categories are high-level and descriptive in nature, they might serve as checklists when identifying examples to guide hypothetical and exploratory work on disease development and progression.

Examples of classical disease categories are as follows:

By organ or organ system: Cardiovascular, central nervous system, pulmonary, musculoskeletal, gastrointestinal, hematologic, genitourinary, endocrinologic, metabolic, renal, dermatologic. This disease category is often thought to be based on the defining cell types of the different organs or organ systems.

By etiology and pathophysiology: Inflammatory, dysfunctional, degenerative, neoplastic, infectious, toxicological. This disease category suggests different disease origination pathways or entry points. For example, infectious and toxicologic diseases have external origins, others have internal origins.

By duration: Acute vs. chronic. This category refers at the existence of short-term or continuous disease development and progression. For example, common infectious diseases are typically acute, whereas degenerative and dysfunctional diseases are typically chronic.

By general characteristics: Continuous (non-episodic) vs. non-continuous (episodic), and progressive vs. non-progressive. This category suggests different degrees of symptomatic manifestations or different rates of disease progression.

By prevalence: Rare vs. common. Most rare disease occur early in life and can be catastrophic, e.g., inborn metabolic errors, while most common diseases occur in adult life. Examples include phenylketonuria (rare) and osteoarthritis (common).

By severity: For example, as exemplified by assessments of unmet medical need (e.g., life expectancy, disease burden). This general category describes to what extent diseases impart serious limitations on physiologic functions and economic wherewithal.

Disease Categories in Systems Therapeutics

An initial review of these disease categories or descriptions suggests that they are not likely to be useful for our objective of better understanding disease initiation, disease development, and disease progression. This is because these categories are not comprehensive or systematic and they typically address only one aspect or dimension of a disease. Descriptions involving the basic biologic nature of etiologic causes are mostly absent, e.g., those based on types of genetic mutations or protein abnormalities.

Further examination of the disease categories mentioned above suggests that the those addressing duration (acute vs. chronic) and general characteristics (continuous vs. non-continuous and progressive vs. non-progressive) can be lumped together since both involve disease activity or changes in these over time. The categories based on etiology and pathophysiology, prevalence and severity represent different aspects of disease pathophysiology. Thus, we have three general disease categories, as shown in Chart 1, i.e., organ system, pathophysiology and activity/time. Note that the biologic modifiers sex and age, discussed in another report (2), are also included in Chart 1.

Chart 1. The general disease categories organ system, pathophysiology and activity/time are superimposed on the pathophysiologic part of the systems therapeutics diagram. The biologic modifiers sex and age are also shown.


The present report has provided outlines of different disease categories and explored where to place these within the systems therapeutics scheme, as illustrated in Chart 1. As has been mentioned these categories are not thought to be generally useful, although the characteristics of individual diseases are essential for better understanding of disease development and progression.


  1. Bjornsson TD. Systems Therapeutics: Framework, Diagram, Categories, Definitions, Examples., January 2023
  2. Bjornsson TD. Systems Therapeutics and Disease Modifiers. Medium, 9 July 2023