MedlinePlus Connect: Planning for Clinical Coding System Changes

DIFFERENCES BETWEEN ICD-9-CM AND ICD-10-CM

Table 1 outlines several of the differences between ICD-9-CM and ICD-10-CM. For instance, the number of codes significantly increased from approximately 14,500 codes to approximately 69,000 codes for reasons including laterality, greater specificity, and specific encounter extensions (initial, subsequent, sequelae).

Table : Comparison of ICD-9-CM and ICD-10-CM*
Category	ICD-9-CM	ICD-10-CM
Length	3-5 Numeric Characters (plus V & E codes)	3-7 Alphanumeric Characters
Size	Approximately 14,500 codes	Approximately 69,000 available codes
Structure	First digit may be alpha (E or V) or numeric; digits 2-5 are numeric	Digit 1 is alpha; digits 2 and 3 are numeric; digits 4-7 are alpha or numeric
Flexibility	Limited space for adding new codes	Flexible for adding new codes
Granularity	Granular	Very granular
Laterality	Lacks laterality	Has laterality (i.e., codes identifying right vs. left)

*Modified table based on the table from p. 1 [8]. Numbers from [9].

CMS writes that ICD-10-CM includes a number of improvements including “the addition of information relevant to ambulatory and managed care encounters; expanded injury codes; the creation of combination diagnosis/symptom codes…;… incorporation of common 4th and 5th digit sub classifications;…and greater specificity in code assignment” [10]. ICD-10-CM updated its organization and categorization of diseases and uses more appropriate disease descriptions [7]. Some code sections changed while others, such as infectious disease, neoplasm, eye and ear codes, are similar in ICD-10-CM and ICD-9-CM [9, 6, 4]. Changes include an increase in diabetes codes (E05, E09, E10, E11, E13) and expanded injury, alcohol and substance abuse, and postoperative complications sections [4]. ICD-10-CM restructured chapters, such as Obstetrics [9]. Injuries in ICD-10-CM are now “grouped by body part rather than by categories of injury” [4, p. 2]. For example, in ICD-9-CM, all fractures, dislocations, or sprains and strains were grouped together regardless of body location. In ICD-10-CM, the type of injury falls under the body location. Fractures are no longer in one location but within each body location (e.g., Injuries to the head (S00 – S09)).

In addition, several chapters significantly increased in number of codes. Figure 1 from Steven Steindel [6] illustrates the relative increase in the number of terms per ICD-10-CM chapter (shown in the black bars). The ICDs are structured according to chapters, with each chapter representing a different body system or disease category (neoplasm, etc.). The figure shows how many times bigger each ICD-10 (international version) and ICD-10-CM (US version) chapter is than the corresponding ICD-9-CM chapter. While based on older data and the numbers have changed with new releases, the table illustrates the drastic changes. Several chapters grew more than 5 times longer in the transition from ICD-9-CM to ICD-10-CM, including (international chapter numbers in parentheses):

• 
  (XIII) M00-M99: Diseases of the musculoskeletal system and connective tissue,
  
• 
  (XV) O00-O9A: Pregnancy, childbirth, & puerperium
  
• 
  (XIX) S00-T88: Injury, poisoning, and certain other consequences of external causes
  
• 
  (XX) V00-Y99: External causes of mortality
  

Figure : Relative increase in terms of the international version, ICD-10-CM versus ICD-9-CM*



Figure from [6] Steindel S. International classification of diseases, 10^th edition, clinical modification and procedure coding system: descriptive overview of the next generation HIPAA code sets. J Am Med Inform Assoc. 2010 May; 17(3): 274–282.doi: 10.1136/jamia.2009.001230

The change to ICD-10-CM from ICD-9-CM includes the replacement of ICD-9-CM Volume 3 by ICD-10 procedure coding system (PCS) [6, p. 275]. While the new ICD-10-PCS codes are an important change to ICD-10-CM/PCS, the MedlinePlus Connect team will not focus on ICD-10-PCS since the team's primary focus is on problem lists (diagnoses), medication lists, and laboratory results.

Many of these changes (e.g., laterality, encounter identification) will not have a major impact on MedlinePlus Connect’s ability to map to ICD-10-CM codes but the dramatic expansion and reorganization will certainly affect how quickly MedlinePlus Connect can support ICD-10-CM. MedlinePlus Connect’s current mapping methods and available technology require each individual ICD code to be explicitly mapped to up to three specific Health Topics. The lack of dynamic processing and automatic application of Health Topics to a swatch of similar codes means that the increase in the number of codes will require a significant amount of manual work and review for MedlinePlus Connect to support ICD-10-CM.

APPENDIX C: SUGGESTED READING LIST provides additional information regarding the ICDs, mapping, and the research discussed in the methodology section.