What is the difference between Postoperative Condition (POCd) and Postoperative Day (POD)?

Difference Between POCD and POD

POCD (Postoperative Cognitive Dysfunction) refers to cognitive decline measured by neuropsychological testing occurring 30 days to 12 months after surgery, while POD (Postoperative Delirium) is an acute fluctuating disturbance in consciousness and attention occurring during hospitalization up to 1 week post-surgery or until discharge. 1, 2

Key Distinguishing Features

Timing of Onset

• POD occurs acutely during the immediate postoperative hospitalization period (up to 1 week or until discharge, whichever comes first) 1
• POCD is diagnosed from 30 days to 12 months after surgery (the updated nomenclature now calls this "postoperative mild or major neurocognitive disorder") 1
• Delayed neurocognitive recovery is the term used for cognitive decline occurring before 30 days postoperatively 1

Clinical Presentation

• POD manifests as disturbed consciousness with reduced ability to focus, sustain, or shift attention, with fluctuating symptoms over hours to days 2
• POCD presents as objectively measured cognitive decline on neuropsychological testing compared to preoperative baseline, without the acute fluctuating consciousness changes seen in delirium 3, 4

Diagnostic Criteria

• POD requires DSM-5 delirium criteria: acute onset, fluctuating course, inattention, and either cognitive changes or perceptual disturbances 2
• POCD (now termed postoperative neurocognitive disorder) requires three components: subjective cognitive complaint, objective impairment (1-2 standard deviations below norms for mild, ≥2 for major), and assessment of instrumental activities of daily living 1, 5

Level of Consciousness

• POD involves disturbed level of consciousness as the most reliable distinguishing feature 2
• POCD occurs without disturbance in consciousness—patients are alert but demonstrate measurable cognitive decline 4

Duration and Course

• POD typically resolves within days to weeks, though it can persist beyond discharge (termed "persistent delirium" which retains the postoperative specifier) 1
• POCD may be transient but can last several months and is associated with premature departure from the workforce and increased mortality 3

Clinical Pitfalls to Avoid

Do not confuse emergence delirium with postoperative delirium—a lucid interval after emergence from anesthesia is not mandatory for POD diagnosis, though it should be documented when present 1

Recognize that POD and POCD can coexist—having delirium does not exclude the possibility of developing cognitive dysfunction later, and both share inflammatory markers like elevated CRP and IL-6 6

Age is the only consistently reported risk factor for POCD, while POD occurs in 15-53% of older surgical patients, particularly after major orthopedic surgery 2, 3, 4

Updated Nomenclature Framework

The British Journal of Anaesthesia published consensus recommendations in 2018 establishing a time-based framework 1:

• Immediate postoperative period (up to 1 week/discharge): Postoperative delirium
• Early recovery (up to 30 days): Delayed neurocognitive recovery
• Expected recovery (30 days to 12 months): Postoperative mild or major neurocognitive disorder (formerly POCD)
• Beyond 12 months: Mild or major neurocognitive disorder (postoperative specifier only applies if diagnosed before 12 months)

The term "postoperative" indicates only a temporal relationship, not causation, which is critical for accurate documentation and avoiding medicolegal implications 1