What is the best ICD (International Classification of Diseases) code for approval when prescribing Linzess (linaclotide)?

Best ICD Codes for Linzess (Linaclotide) Approval

The best ICD-10 code for Linzess (linaclotide) approval is K58.9 (Irritable bowel syndrome with constipation) as this aligns with its FDA-approved indication and provides the highest likelihood of insurance coverage.

Primary Indications for Linzess (Linaclotide)

• Linaclotide is FDA-approved and strongly recommended as a second-line treatment for irritable bowel syndrome with constipation (IBS-C) 1, 2
• Linaclotide is also approved for chronic idiopathic constipation (CIC) 1
• The 290 μg dose is specifically indicated for IBS-C, while lower doses (72-145 μg) are used for CIC 2, 3

Appropriate ICD-10 Codes for Linzess Approval

Primary Codes (Most Likely to Be Approved):

• K58.9 - Irritable bowel syndrome without diarrhea (includes IBS-C)

  • This is the most appropriate code for linaclotide's primary indication 1, 3
  • Strong clinical evidence supports linaclotide use for this condition 4, 5

• K59.00 - Constipation, unspecified

  • Appropriate for chronic idiopathic constipation cases 1
  • May require additional documentation to justify medical necessity

Secondary Codes (May Require Additional Documentation):

• K59.04 - Chronic idiopathic constipation
  • More specific than K59.00 and directly aligns with linaclotide's second indication 1
  • May be preferred by some insurance carriers for clarity

Documentation Requirements for Approval

• For IBS-C (K58.9):

  • Document symptoms consistent with Rome criteria for IBS-C 1, 3
  • Document failure of first-line treatments (fiber, PEG) 3
  • Document severity of symptoms affecting quality of life 2

• For CIC (K59.00 or K59.04):

  • Document duration of constipation (≥3 months) 1
  • Document failure of over-the-counter laxatives 1
  • Document specific symptoms (straining, hard stools, incomplete evacuation) 1

Common Pitfalls to Avoid

• Avoid using K58.0 (IBS with diarrhea) - This is contradictory to linaclotide's indication and will likely result in denial 1, 3
• Avoid using K59.1 (Functional diarrhea) - Linaclotide can cause diarrhea as a side effect but is not indicated to treat diarrhea 4
• Avoid using K50-K52 codes (inflammatory bowel disease) - Linaclotide is not indicated for IBD and may be contraindicated 6

Insurance Coverage Considerations

• Most insurance plans require prior authorization for linaclotide due to its cost (~$523/month) 1
• Documentation of failed first-line therapies is typically required 3
• Some plans may require step therapy with less expensive alternatives like lubiprostone before approving linaclotide 1
• Consider the specific dose being prescribed, as this may affect which ICD code is most appropriate (290 μg for IBS-C vs. lower doses for CIC) 2