Z91.81
Z91 — Personal risk factors, not elsewhere classified
Chapter 21: Factors Influencing Health Status and Contact with Health Services (Z00-Z99)
Z77-Z99 — Persons with potential health hazards related to family and personal history and certain conditions influencing health status
Clinical Definition
History of falling is a clinical risk factor designation used to identify patients who have experienced one or more falls in the recent past and are therefore at elevated risk for future falls and fall-related injuries. Falls are a leading cause of morbidity and mortality among older adults, contributing to fractures (particularly hip fractures), traumatic brain injuries, loss of independence, and increased healthcare utilization. The documentation of fall history is essential for triggering appropriate risk assessments, preventive interventions, and care planning.
ICD-10-CM code Z91.81 is a supplementary Z-code used to capture the personal history of falling as a risk factor. It is not a disease diagnosis but rather a health status code that communicates fall risk to other providers and supports medical necessity for fall prevention services. This code is typically used alongside other diagnosis codes rather than as a sole primary diagnosis. It is distinct from R29.6 (repeated falls), which is used as an active clinical finding when the patient presents with recurrent falls as a current problem requiring evaluation, and from the W-codes (W00-W19) that identify the external cause of a specific fall event.
Medicare Annual Wellness Visits (AWV) include fall risk screening as a required component. Documentation of fall history supports referrals for physical therapy, home safety evaluations, medication reviews (particularly for medications that increase fall risk such as sedatives, antihypertensives, and psychotropics), vision assessments, and assistive device evaluations. Fall prevention programs have been shown to reduce fall rates by 20-30% in community-dwelling older adults.
When to Use Z91.81
- ✓The patient has a documented history of one or more falls and the provider notes this as a risk factor in the medical record.
- ✓During a Medicare Annual Wellness Visit (AWV) or preventive care encounter where fall history is identified through screening questionnaires.
- ✓As a supplementary code to communicate fall risk when the patient is being seen for another condition, and the fall history is relevant to the encounter (e.g., medication management, physical therapy referral).
- ✓The provider documents 'history of falls,' 'fall risk,' or 'recurrent falls — resolved' as a background risk factor, not as the primary reason for the visit.
- ✓When coding for fall prevention services (physical therapy, home safety evaluation, assistive device prescription) where the history of falling establishes medical necessity.
Common Coding Mistakes
- ⚠Using Z91.81 as the primary diagnosis for an encounter where the patient presents with an active fall or recurrent falling as the chief complaint — use R29.6 (repeated falls) instead when falls are the active problem being evaluated.
- ⚠Confusing Z91.81 with W19.XXXA (unspecified fall, initial encounter) — W-codes are external cause codes used to identify a specific fall event and its circumstances, while Z91.81 documents a personal history of falls as a risk factor.
- ⚠Using Z91.81 when the patient presents after an acute fall for injury evaluation — the acute injury codes and W-codes should be used for the current fall event, not the history code.
- ⚠Using R29.6 (repeated falls) and Z91.81 interchangeably — R29.6 is a symptom code for active recurrent falls that warrants workup, while Z91.81 is a risk-factor code for past fall history.
- ⚠Failing to document the fall history altogether — many providers do not code fall risk despite screening for it, which leads to missed opportunities for fall prevention referrals and underreporting of fall risk in the patient's problem list.
Related & Differential Codes
| Code | Description | Relationship |
|---|---|---|
| R29.6 | Repeated falls | Related |
| W19.XXXA | Unspecified fall, initial encounter | Related |
| W19.XXXD | Unspecified fall, subsequent encounter | Related |
| W18.30XA | Fall on same level, unspecified, initial encounter | Related |
| R26.0 | Ataxic gait | Related |
| R26.2 | Difficulty in walking, not elsewhere classified | Related |
| R26.81 | Unsteadiness on feet | Related |
| M62.81 | Muscle weakness (generalized) | Related |
| R42 | Dizziness and giddiness | Related |
| H81.10 | Benign paroxysmal positional vertigo, unspecified ear | Related |
| Z87.39 | Personal history of other musculoskeletal disorders | Related |
Documentation Requirements
- 1Fall history: document the number of falls, timeframe (e.g., 'two falls in the past 6 months'), and circumstances surrounding the falls (location, time of day, activity at the time).
- 2Fall risk assessment tool results: document the score from a validated screening tool such as the Timed Up and Go (TUG), Morse Fall Scale, STEADI toolkit, or Berg Balance Scale.
- 3Contributing factors: document identified fall risk factors including medications (sedatives, antihypertensives, psychotropics), vision impairment, orthostatic hypotension, gait or balance disorders, lower extremity weakness, cognitive impairment, and environmental hazards.
- 4Injury history: document whether prior falls resulted in injuries (fractures, head trauma, lacerations) and the severity of those injuries.
- 5Current functional status: document the patient's mobility level, use of assistive devices, and ability to perform activities of daily living.
- 6Interventions and referrals: document fall prevention measures implemented, including physical therapy referrals, home safety modifications, medication adjustments, vision correction, and assistive device prescriptions.
Reimbursement & Billing Notes
ICD-10-CM code Z91.81 is a valid, billable code accepted by Medicare, Medicaid, and commercial payers. It is commonly used as a secondary diagnosis to support medical necessity for fall prevention services, including physical therapy evaluations, gait training, balance exercises, home safety assessments, and assistive device prescriptions. During Medicare Annual Wellness Visits, fall risk screening is a required component, and Z91.81 can be reported alongside the AWV codes (G0438/G0439) when fall history is identified.
Z91.81 does not map to a CMS-HCC risk adjustment category and therefore does not directly impact capitated payment. However, accurate documentation and coding of fall risk supports quality measure reporting under MIPS and other value-based programs that include fall screening measures. Additionally, documentation of fall history is important for medical-legal purposes, patient safety, and care coordination between providers.
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Try Free — No Credit Card RequiredFrequently Asked Questions
What is the ICD-10 code for fall risk?
The ICD-10-CM code for history of falling (commonly referenced as 'fall risk') is Z91.81. This is a Z-code used to document a personal history of falls as a risk factor. It is not used for an active fall event or for the initial encounter for a specific fall injury — those situations use external cause codes from the W00-W19 range.
What is the difference between Z91.81 and R29.6?
Z91.81 (history of falling) is a risk-factor code used to document a patient's past fall history, typically as a supplementary code to flag fall risk for preventive planning. R29.6 (repeated falls) is a symptom/sign code used when recurrent falls are an active clinical problem being evaluated at the current encounter. Use R29.6 when the patient presents with ongoing falls requiring workup, and Z91.81 when the fall history is a background risk factor.
Can Z91.81 be used as a primary diagnosis?
Z91.81 can technically be listed as a primary diagnosis, but it is most commonly used as a secondary or supplementary code alongside other diagnoses. For example, during an encounter for physical therapy for balance training, the primary diagnosis might be R26.81 (unsteadiness on feet) with Z91.81 as a supplementary code to document the fall history that supports the referral. During a Medicare AWV, the AWV code is the primary service, and Z91.81 is added when fall history is identified.
What is the ICD-10 code for recurrent falls in elderly?
For an elderly patient actively experiencing recurrent falls as a current clinical problem, use R29.6 (repeated falls). If the recurrent falls are being documented as a historical risk factor rather than the active reason for the encounter, use Z91.81 (history of falling). Many encounters for older adults will include both codes — R29.6 if falls are actively being evaluated, and Z91.81 if falls are a documented risk factor in the medical history.
When should fall history be documented during an AWV?
Fall risk screening is a required component of the Medicare Annual Wellness Visit. During the AWV, the provider should ask the patient about falls in the past 12 months, assess gait and balance (using tools like the Timed Up and Go test), and identify modifiable risk factors. If the patient reports a history of falls, Z91.81 should be added to the encounter's diagnosis list. If active recurrent falls are identified, R29.6 should also be considered. This documentation supports referrals for fall prevention services.
Does Z91.81 affect Medicare risk adjustment?
Z91.81 does not map to a CMS-HCC risk adjustment category in the standard V28 model and therefore does not directly impact Medicare Advantage capitated payments or RAF scores. However, documenting fall history is important for quality measure reporting, care coordination, and supporting medical necessity for fall prevention services. The conditions contributing to fall risk (such as gait disorders, muscle weakness, or vestibular disorders) may have their own HCC mappings.