What Is Clinical Documentation Improvement (CDI)?
Clinical documentation improvement (CDI) is the process of reviewing a patient's medical record, usually while the patient is still in the hospital, and asking physicians to clarify incomplete, vague, or conflicting documentation so that the record accurately reflects the patient's condition and the care delivered. The output of CDI is a complete record that supports correct code assignment, appropriate reimbursement, and reliable quality data. HMI LLC delivers CDI work to hospitals through its documentation assessment, coding review, and provider education services.
The profession now prefers the phrase "clinical documentation integrity," and the two terms are used interchangeably. The Association of Clinical Documentation Integrity Specialists (ACDIS) and the American Health Information Management Association (AHIMA) both use the integrity wording, and since 2023 ACDIS has operated as part of the AHIMA Enterprise. The shift in language is deliberate: the goal of a CDI program is an accurate record, not a higher-paying one.
Why Clinical Documentation Improvement Matters to a Hospital
Documentation quality directly determines what a hospital is paid, how its quality scores read, and how it fares under audit. Under Medicare's MS-DRG system, a single documented secondary diagnosis moves an inpatient stay into a higher severity level, and a missing or unsupported diagnosis leaves revenue on the table or creates repayment exposure. CDI exists to make sure the record says exactly what happened, no more and no less.
The financial stakes are large. According to the HHS Office of Inspector General's February 2021 report on inpatient billing trends (OEI-02-18-00380), Medicare spent $109.8 billion on 8.7 million inpatient hospital stays in fiscal year 2019, and nearly half of that spending went to stays billed at the highest severity level. The same report found that the number of stays at the highest severity level increased almost 20 percent from FY 2014 through FY 2019, and that over half of those stays had only one diagnosis qualifying them for payment at that level. OIG flagged that pattern as vulnerable to upcoding and recommended more targeted audits.
That finding cuts both ways for a hospital. A stay coded at the highest severity on the strength of one diagnosis is exactly what a RAC or other auditor will test. A CDI program that confirms clinical indicators support each documented condition protects the hospital when the RAC demand letter arrives. A hospital with no CDI function often has the opposite problem: legitimate conditions that were treated but never documented in codable language.
How a CDI Program Works Day to Day
A CDI program reviews records concurrently, identifies documentation gaps against clinical indicators in the chart, and sends compliant written queries to providers asking them to clarify or confirm a diagnosis. The provider answers, the record is amended, and the coder assigns codes to the completed documentation. Programs track query volume, provider response rate, and agreement rate as their core metrics.
The query is the central tool. AHIMA and ACDIS jointly publish the Guidelines for Achieving a Compliant Query Practice, which require that a query present the relevant clinical indicators, offer clinically reasonable options including "unable to determine" or "other," and avoid leading the provider toward a specific answer. AHIMA's Body of Knowledge states that proper responses to queries "result in improved accuracy and completeness in documentation, coding, reimbursement, as well as severity of illness (SOI) and risk of mortality (ROM) classifications."
Response and agreement rates show how well a program is working. According to the ACDIS 2023 CDI Week Industry Survey of 781 respondents, 60.09% of CDI programs reported a provider query response rate of 91 to 100 percent, up from 55.97% the prior year, and 38.49% reported a provider agreement rate of 91 to 100 percent. The same survey found that 34.54% of CDI departments report to revenue integrity or revenue cycle leadership and 17.67% report to HIM or coding, which shows how tightly CDI is bound to both the financial and the health information functions of a hospital.
Where CDI Lives on the Org Chart
CDI is a mid-revenue-cycle function. It happens after the patient is admitted and before the claim is coded and billed. Most programs are staffed by registered nurses or experienced coding professionals holding the CCDS credential from ACDIS or the CDIP credential from AHIMA, with a physician advisor engaging the medical staff. ACDIS reports that about 27% of programs also review some outpatient setting or service, an area that continues to grow as risk-adjusted payment models spread.
CDI Versus Medical Coding: What Each One Does
CDI and medical coding are separate disciplines that depend on each other: CDI shapes the documentation while care is delivered, and coding translates the finished documentation into ICD-10-CM, ICD-10-PCS, and CPT codes after discharge. Coders cannot assign a code to a condition the physician never documented, and they cannot infer a diagnosis from lab values or medication orders. CDI closes that gap by asking the provider to state what the clinical picture supports.
A hospital that invests in coding accuracy without CDI hits a ceiling. The best coder in the country can only code what the chart says. A hospital that runs CDI without strong coding review has the reverse problem: clarified documentation that is still coded or sequenced incorrectly, which shows up in inpatient and outpatient coding reviews as MS-DRG, POA indicator, and medical-necessity errors. Mature programs run both, and they measure the two functions together.
How HMI LLC Approaches Clinical Documentation Improvement
HMI LLC delivers clinical documentation improvement as an assessment-and-education service rather than a software product: credentialed U.S.-based specialists review a hospital's documentation processes and medical records for completeness across physician and clinical staff, then provide education to the staff who write the record. The work is part of HMI's compliance services and is paired with coding compliance review and physician E/M documentation review.
That model fits hospitals that cannot justify a standing CDI department. Critical access hospitals, small acute care facilities, and physician groups get a documentation assessment, a set of findings, and provider education that stays in place after the engagement ends. HMI has done this work since 1989, and its leadership includes Vickie Faler, RHIT, CPC, CDEO, who holds the AAPC Certified Documentation Expert Outpatient credential and has provided physician documentation and coding education for decades. Every HMI specialist is U.S.-based and holds an industry credential such as RHIT, CCS, CPC, or CHC.
Frequently Asked Questions
What is the difference between CDI and medical coding? CDI works on the documentation before or while the patient is being treated; coding translates the finished documentation into ICD-10-CM, ICD-10-PCS, and CPT codes after discharge. CDI specialists ask physicians to clarify vague or incomplete entries. Coders assign codes only to what the record states. The two functions depend on each other: coding accuracy is capped by documentation quality.
What is a CDI query? A CDI query is a formal, written request asking a physician or other provider to clarify, confirm, or add detail to a diagnosis or procedure in the medical record. Compliant queries present the clinical indicators, offer clinically reasonable options including "unable to determine," and never lead the provider toward a specific answer. AHIMA and ACDIS publish joint guidelines for compliant query practice.
Is CDI the same as clinical documentation integrity? Yes. The profession has largely shifted from "clinical documentation improvement" to "clinical documentation integrity" to signal that the goal is an accurate record, not a higher-paying one. Both phrases share the CDI abbreviation and describe the same function: concurrent and retrospective review of the record with physician queries to resolve gaps.
Do small and rural hospitals need a CDI program? Yes. Any hospital paid under MS-DRGs is paid according to what its documentation supports, regardless of size. Small and critical access hospitals rarely staff a dedicated CDI department, so they typically rely on periodic documentation assessments, focused coding reviews, and physician education delivered by an outside HIM partner such as HMI LLC.
Who performs clinical documentation improvement? CDI is performed by credentialed clinical documentation specialists, most of whom are registered nurses or experienced coding professionals. According to the ACDIS 2023 CDI Week Industry Survey, 74.13% of the 781 respondents hold an RN credential. Common CDI credentials include the CCDS from ACDIS and the CDIP from AHIMA. Physician advisors support the program by engaging medical staff.
Clinical documentation improvement is the discipline that makes a hospital's medical record say what actually happened, in language that codes correctly and holds up under audit. Hospitals that want a documentation assessment, coding compliance review, or provider education without building a full CDI department can talk with HMI LLC about where their documentation exposure is today.