When pupillometry indices disagree: does QPi add prognostic information beyond NPi? - Summary - MDSpire
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When NPi and QPi diverge: Does QPi provide prognostic value beyond NPi?

  • By

  • Li-Xia Xu

  • October 19, 2026

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Objective:

Assess whether QPi adds prognostic information when it disagrees with NPi, or whether discordance mainly reflects differing sensitivity to measurement effects.

Approach:
  • Study context: The letter discusses the prospective, multicentre LYNX study of NPi and QPi in patients with acute brain injury.
Key Findings:
  • Across 7,089 paired measurements, NPi and QPi were moderately to strongly correlated (r = 0.717).
  • Abnormal measurements were more frequent with QPi than NPi (median proportions: 12.7% versus 1.2%).
  • Each index was independently associated with unfavourable six-month neurological outcomes in separate adjusted models.
  • QPi was more sensitive to anaesthetic exposure, which can complicate interpretation of discordant readings.
Interpretation:

The reported associations do not establish whether abnormal QPi with normal NPi identifies higher-risk patients or adds prognostic information beyond NPi and conventional clinical assessment. Discordance could reflect pharmacological effects, device-dependent variation, or a potentially informative physiological signal.

Limitations:
  • The described results do not directly assess the prognostic value of discordant readings within individual patients.
  • The threshold of 3 was established for NPi, not QPi; comparisons using it for QPi are exploratory.
  • Anaesthetic sensitivity may confound interpretation of QPi abnormalities.
Conclusion:

The letter calls for analyses of discordant paired readings to clarify whether QPi provides interpretable prognostic information beyond NPi.

Sources:

Original Source(s)

When pupillometry indices disagree: does QPi add prognostic information beyond NPi?

  • by Li-Xia Xu

  • October 19, 2026

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