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Please fill out this form if you're interested in either supporting this proposal as it exists or if you have suggestions you'd like to make.

This proposal is regarding the ICD-10-CM Official Guidelines for Coding and Reporting (OCG) in the United States. The guidelines are reviewed and approved yearly by the four organizations that make up the Cooperating Parties for the ICD-10-CM: the American Hospital Association (AHA), the American Health, Information Management Association (AHIMA), Centers for Medicare and Medicaid Services (CMS), and National Center for Health Statistics (NCHS). They will review this proposal (which was finalized March 31st, 2024) and let us know their response.

Please feel free to email for any further questions.

R69 - “Illness, unspecified” 

Challenges in Measuring Diagnostic Uncertainty 

Although diagnostic uncertainty is routinely encountered, it is generally poorly defined, poorly understood and therefore not well-quantified in a clinical setting(1). In 2017, a systematic review was performed to understand the way diagnostic uncertainty is defined and measured in the medical literature and 123 publications were identified for full review without a single definition of diagnostic uncertainty. Highlighting this significant gap, the authors then proposed a definition of diagnostic uncertainty as a “subjective perception of an inability to provide an accurate explanation of the patient’s health problem.” More recently, another definition was provided as “you wouldn’t be surprised if the patient had a different diagnosis that required a change in management.”(2) Prior to these definitions, some attempts to measure diagnostic uncertainty have relied on careful visit note review looking for question marks or language like “maybe,” “unclear,” or “unclear etiology.”(3) Estimates using different measures and in different settings range from 11-19% uncertain diagnoses.(2,3) More effective use of the ICD-10 code R69 to denote a certain degree of diagnostic uncertainty, would allow more rapid evaluation of how many cases at a given point in time are diagnostically uncertain, “undiagnosed,” “not yet diagnosed,” and/or “illness, unspecified.”

Diagnostic Uncertainty in Rare Disease Diagnosis 

The path to diagnosis for patients with rare diseases often involve misdiagnoses, delayed diagnosis, missed diagnoses, and conflicting medical opinions.(4) As there is difficulty in the process of diagnosis in general, difficulty in defining diagnostic uncertainty and difficulty in the communication of uncertainty to families seeking diagnosis,(5) it is reasonable to surmise that these difficulties could be exacerbated in the case of rare diseases likely contributing to lengthy durations to diagnosis. It can take an average of over 6 years to become properly diagnosed with a rare disease and while the “diagnostic odyssey” is well-known to the rare disease community, the costs of this lengthy period of diagnostic uncertainty have only recently been estimated. Delayed diagnoses have been estimated to cost between $87,000-$517,000 in avoidable costs per person in the US.(6) In the UK, the total hospital activity levels and costs for rare disease patients 10 years pre-diagnosis were just over double that of a population matched comparator cohort.(7) 

Diagnostic Uncertainty codified by R69 

If a person could have diagnostic uncertainty denoted toward the beginning of their diagnostic odyssey, with sufficient follow-up actions, we could see a reduction in both costs and in time to diagnose rare diseases (and other difficult to diagnose conditions). Such a workflow is not without precedent as in Serbia, if doctors cannot find a proper diagnosis within six months, doctors are obliged to take follow-up action by sending tissue and blood to clinics outside of Serbia.(8) 


Proposed Changes 

We propose the use of the ICD-10 code R69 “illness, unspecified” to be used to address some of the above-described challenges. The following, non tabular suggestion is being made:

The ICD-10-CM official guidelines for coding and reporting FY 2023 -- UPDATED April 1, 2023, provides a description of how coding should be handled when encountering an Uncertain Diagnosis: 

“H. Uncertain Diagnosis 

If the diagnosis documented at the time of discharge is qualified as “probable,” “suspected,” “likely,” “questionable,” “possible,” or “still to be ruled out,” “compatible with,” “consistent with,” or other similar terms indicating uncertainty, code the condition as if it existed or was established.”(9) 

If, instead, the most likely diagnosis is coded “as if it existed or was established,” AND is additionally coded with R69 to signify that it remains an unspecified illness, this could provide the foundation to much more rapidly acquire data about unspecified illnesses, diagnostic uncertainty, and likely diagnostically uncertain cases representing rare diseases before they are diagnosed as such.


Expected Outcomes for Healthcare Systems

If doctor's start regularly using the R69 code, we can get better measurements on how many patients are still in this "uncertain" stage of diagnosis and we can utilize algorithms and emerging technology to ensure proper follow-up with patients who have R69 somewhere in their history. 


Please see below for list of supporting individuals and organizations.


1. Bhise V, Rajan SS, Sittig DF, Morgan RO, Chaudhary P, Singh H. Defining and Measuring Diagnostic Uncertainty in Medicine: A Systematic Review. J Gen Intern Med. 2018;33(1):103-115. 

2. Ipsaro AJ, Patel SJ, Warner DC, et al. Declaring Uncertainty: Using Quality Improvement Methods to Change the Conversation of Diagnosis. Hosp Pediatr. 2021;11(4):334-341. 

3. Whaley LE, Businger AC, Dempsey PP, Linder JA. Visit complexity, diagnostic uncertainty, and antibiotic prescribing for acute cough in primary care: a retrospective study. BMC Fam Pract. 2013;14:120. 

4. Rare Disease Impact Report: Insights from patients and the medical community. Global Genes. Published 04/2013. Accessed 12/2023. 

5. Young EE, Kane J, Timmons K, et al. Brief report: Improving communication of diagnostic uncertainty to families of hospitalized children. Diagnosis (Berl). October 2023. doi:10.1515/dx-2023-0088 

6. Delayed Diagnosis Study. EveryLife Foundation for Rare Diseases. Published September 5, 2023. Accessed December 1, 2023. 

7. Mendelian, Finding undiagnosed patients early. The Cost of Undiagnosed rare diseases. Published January 27, 2019. Accessed December 2, 2023. 

8. Adopting Zoja’s law. Center for the Study of Bioethics. Accessed December 1, 2023. 

9. ICD-10-CM official guidelines for coding and reporting FY 2023 -- UPDATED April 1, 2023 (October 1, 2022 - September 30, 2023). April 2023. Accessed December 1, 2023.

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