About OIICS

The Occupational Injury and Illness Classification System (OIICS) was developed by the Bureau of Labor Statistics (BLS) to provide a standardized coding system for characterizing work-related injuries and illnesses. The OIICS has four component hierarchical coding structures or “code trees.” Each structure is used to characterize specific incident concepts (referred to here as coding components). Two coding structures are used to describe the characteristics of the injury or illness (i.e., "Nature" and "Part of Body Affected") and two structures are used to describe the incident circumstances (i.e., "Source/Secondary Source of injury or illness", and "Event or Exposure"). The Source and Secondary Source coding components utilize the same hierarchical coding structure. However, the coding rules differ slightly. Thus, the four coding structures represent five data elements or conceptual components.

Each coding component is represented by a hierarchical coding structure with up to four levels of detail represented by numeric codes with 1-4 digits. At the highest level of the coding structure are division titles (1 digit) followed by levels with successively more detailed descriptors: major groups (2 digit), groups (3 digit) and finally the fourth level which provides the most specificity for each component in the hierarchical coding structure (4 digit). Category “titles” occur at division, major group, and group levels and are indicated by a numeric code followed by an asterisk (e.g., for Source of injury or illness: 4* PARTS AND MATERIALS, 41* Building materials—solid elements, and 411* Bricks, blocks, structural stone). Codes followed by an asterisk denote a summary-level code not assigned to individual cases. In the example sequence, an individual case would be assigned one of the 4-digit Source codes: 4110 Bricks, blocks, structural stone, unspecified; 4111 Bricks and pavers; 4112 Concrete blocks, cinder blocks; 4113 Stone, marble, granite slabs; 4114 Structural stones or slabs, n.e.c.; or 4119 Bricks, blocks, structural stone, n.e.c. (n.e.c. = not elsewhere classified).

Two subclasses within each of the second through fourth levels are used to classify characteristics that cannot be classified with more specificity (i.e., characteristics that are unspecified; e.g., 4110 Bricks, blocks, structural stone, unspecified) and characteristics that cannot be specifically fit into one of the subclasses (i.e., characteristics that are not elsewhere classified; e.g., 4119 Bricks, blocks, structural stone, n.e.c.). When a group does not lend itself to further subclasses at the third or fourth levels the hierarchical scheme is truncated.

Individual worker injury and illness incidents are coded to two to four digits, depending upon the OIICS component and the amount of information available with which to classify the case. For analysis purposes, similar cases may be grouped at any of the four levels from division titles to the most detailed 4-digit classifications.

Specific coding selection rules are used for each OIICS coding component. Code descriptions and informational notes are provided at numerous levels within each coding structure. The selection rules and informational material are embedded in the graphical tree interfaces provided here as well as in the OIICS manuals. The OIICS manuals also include alphabetical indices for each coding component.