{
  "registry": "KnowYourPrime Evidence Registry",
  "license": {
    "name": "CC BY 4.0",
    "url": "https://creativecommons.org/licenses/by/4.0/",
    "attribution": "Credit KnowYourPrime and link to the finding URL."
  },
  "fields": {
    "devices": "Devices this finding names, including models it says it does not cover. What was actually tested is in scope.applies_to; exclusions are in scope.does_not_cover.",
    "evidence": "Studies by role: anchor (the rating rests on it), conflicting, null_result, supporting.",
    "industry_ties": "Device-maker ties listed in Europe PMC metadata: author_affiliations names makers an author lists as an affiliation, funders names makers listed as funding. stated_ties holds ties a paper states only in its own conflict, funding or acknowledgement text, each read from that statement and worded to say only what it says. Sources are Europe PMC metadata, funding printed in the abstract, and those reviewed statements. An empty list means no tie was found there, not that the study is independent: many papers have no open full text to read. Metadata, not a judgment of the study. checked false means no Europe PMC metadata was available."
  },
  "id": "KYP-ER-0022",
  "version": "1.0",
  "reviewed": "2026-10-24",
  "url": "https://knowyourprime.com/evidence-calibrated-cuffless-blood-pressure-tracking",
  "title": "Do Calibrated Cuffless Blood Pressure Readings Track Real Changes?",
  "question": "After calibration with a cuff, does a smartwatch or bracelet blood pressure reading follow real changes in blood pressure?",
  "measurement": "Blood pressure",
  "devices": [
    "Samsung Galaxy Watch",
    "Aktiia (Hilo)",
    "Somnotouch"
  ],
  "rating": {
    "label": "Uncertain",
    "code": "uncertain",
    "definition": "Evidence is conflicting, inconsistent, or difficult to interpret.",
    "rule_version": "1.6",
    "rule_reasons": [
      "Anchor-grade evidence affirms the core relationship.",
      "An anchor study is present but its own reported finding does not cleanly affirm this claim, so it does not count toward the Established threshold.",
      "The claim rests on a single anchor whose finding affirms it; a second independent affirming anchor is needed to reach Established.",
      "A clean anchor supports this claim, but an unresolved conflicting study contradicts it on the core relationship, so the evidence is treated as in genuine dispute.",
      "Some evidence conflicts on secondary points that do not change the core direction."
    ]
  },
  "conclusion": "Mostly not. Calibrated cuffless devices tend to stay close to the cuff reading they were calibrated with: in 166 people the cuffless 24-hour average sat 1.8 mmHg from the calibration value while the cuff average moved 7.4 mmHg, and the error grew the further real pressure moved. One finger device passed a full set of tracking tests.",
  "reasoning": [
    "A cuffless device calibrated against your cuff can look accurate simply by repeating numbers near the calibration value. The real test is whether it follows a change, after medication or over the day.",
    "A finger photoplethysmography monitor met the European Society of Hypertension scenarios, including a fall in pressure, which is the clean anchor. A month-long Samsung Galaxy Watch 5 study found accuracy declined as values moved from the calibration point, and several studies and two Hypertension reviews found calibrated devices pulled toward their calibration. With a clean anchor and core-hitting conflicts, the rule rates the claim Uncertain."
  ],
  "key_results": [
    {
      "text": "In 166 participants wearing a pulse-transit-time cuffless device and a cuff monitor simultaneously, the mean difference between the calibration reading and the 24-hour average was 7.4 mmHg systolic for the cuff and 1.8 mmHg for the cuffless device, and the cuffless error grew almost linearly with how far pressure had moved.",
      "source": "doi:10.1097/hjh.0000000000003667",
      "source_url": "https://doi.org/10.1097/HJH.0000000000003667",
      "source_citation": "Derendinger et al., Journal of Hypertension, 2024"
    },
    {
      "text": "In 40 patients, a Samsung Galaxy Watch Active 2 showed proportional bias against 24-hour monitoring, overestimating low systolic pressures and underestimating high ones.",
      "source": "doi:10.3389/fcvm.2022.958212",
      "source_url": "https://doi.org/10.3389/fcvm.2022.958212",
      "source_citation": "Falter et al., Frontiers in Cardiovascular Medicine, 2022"
    },
    {
      "text": "In 37 participants measured daily for 28 days after calibration, a Samsung Galaxy Watch 5 was assessed against a validated Omron cuff across its full recalibration interval; the authors report accuracy declined as values diverged from the calibration point.",
      "source": "doi:10.1177/20552076261415923",
      "source_url": "https://doi.org/10.1177/20552076261415923",
      "source_citation": "Walzel et al., Digital Health, 2026"
    },
    {
      "text": "In three people followed through a blood pressure medication increase, a home cuff recorded a large fall that the Aktiia bracelet barely registered.",
      "source": "doi:10.1097/hjh.0000000000003428",
      "source_url": "https://doi.org/10.1097/hjh.0000000000003428",
      "source_citation": "Tan et al., Journal of Hypertension, 2023"
    }
  ],
  "scope": {
    "applies_to": "Cuffless wrist, finger and bracelet devices calibrated against a cuff, and whether their readings follow blood pressure changes after calibration.",
    "does_not_cover": "Watches with a built-in cuff; whether the first reading after calibration is accurate; diagnosis or medication decisions."
  },
  "limitations": [
    "The one fully passing device is a finger monitor, not a consumer smartwatch.",
    "The medication-tracking test followed three people."
  ],
  "evidence": {
    "anchor": [
      {
        "key": "doi:10.1161/jaha.126.050501",
        "title": "Clinical Validation of Photoplethysmography-Based Finger Cuffless Blood Pressure Monitoring Following European Society of Hypertension Recommendations.",
        "first_author": "Qiu",
        "journal": "Journal of the American Heart Association",
        "year": 2026,
        "url": "https://doi.org/10.1161/JAHA.126.050501",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      },
      {
        "key": "doi:10.1177/20552076261415923",
        "title": "Long-term accuracy and stability of blood pressure measurements from a smartwatch: Prospective validation study",
        "first_author": "Šimon Walzel",
        "journal": "Digital Health",
        "year": 2026,
        "url": "https://doi.org/10.1177/20552076261415923",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      }
    ],
    "conflicting": [
      {
        "key": "doi:10.1161/hypertensionaha.125.24822",
        "title": "Cuffless Blood Pressure Measurement: Where Do We Actually Stand?",
        "first_author": "Mukkamala",
        "journal": "Hypertension (Dallas, Tex. : 1979)",
        "year": 2025,
        "url": "https://doi.org/10.1161/HYPERTENSIONAHA.125.24822",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      },
      {
        "key": "doi:10.1097/hjh.0000000000003667",
        "title": "Ability of a 24-h ambulatory cuffless blood pressure monitoring device to track blood pressure changes in clinical practice.",
        "first_author": "Derendinger",
        "journal": "Journal of hypertension",
        "year": 2024,
        "url": "https://doi.org/10.1097/HJH.0000000000003667",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      },
      {
        "key": "doi:10.1097/hjh.0000000000003428",
        "title": "Evaluation of the ability of a commercially available cuffless wearable device to track blood pressure changes",
        "first_author": "Isabella Tan",
        "journal": "Journal of Hypertension",
        "year": 2023,
        "url": "https://doi.org/10.1097/hjh.0000000000003428",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": [
            "conflict statement: Aktiia supplied the devices tested, and two authors have been paid by Aktiia"
          ]
        }
      },
      {
        "key": "doi:10.1038/s41440-023-01215-z",
        "title": "Feasibility and measurement stability of smartwatch-based cuffless blood pressure monitoring: A real-world prospective observational study.",
        "first_author": "Han",
        "journal": "Hypertension research : official journal of the Japanese Society of Hypertension",
        "year": 2023,
        "url": "https://doi.org/10.1038/s41440-023-01215-z",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      },
      {
        "key": "doi:10.1161/hypertensionaha.122.20410",
        "title": "The Microsoft Research Aurora Project: Important Findings on Cuffless Blood Pressure Measurement.",
        "first_author": "Mukkamala",
        "journal": "Hypertension (Dallas, Tex. : 1979)",
        "year": 2023,
        "url": "https://doi.org/10.1161/HYPERTENSIONAHA.122.20410",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      },
      {
        "key": "doi:10.3389/fcvm.2022.958212",
        "title": "Smartwatch-Based Blood Pressure Measurement Demonstrates Insufficient Accuracy",
        "first_author": "Maarten Falter",
        "journal": "Frontiers in Cardiovascular Medicine",
        "year": 2022,
        "url": "https://doi.org/10.3389/fcvm.2022.958212",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      }
    ],
    "supporting": [
      {
        "key": "doi:10.1080/08037051.2026.2707794",
        "title": "Long-term stability and blood pressure change tracking with a cuffless wearable device in hypertensive patients.",
        "first_author": "Proença",
        "journal": "Blood pressure",
        "year": 2026,
        "url": "https://doi.org/10.1080/08037051.2026.2707794",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [],
          "funders": [],
          "stated_ties": []
        }
      },
      {
        "key": "doi:10.1093/ajh/hpaf003",
        "title": "Continual Versus Occasional Blood Pressure (COOL-BP) in Remote Hypertension Management.",
        "first_author": "Unlu",
        "journal": "American journal of hypertension",
        "year": 2025,
        "url": "https://doi.org/10.1093/ajh/hpaf003",
        "industry_ties": {
          "checked": true,
          "author_affiliations": [
            "Aktiia"
          ],
          "funders": [
            "Aktiia"
          ],
          "stated_ties": []
        }
      }
    ]
  },
  "evidence_last_evaluated": "Oct 19, 2026",
  "rating_history": [
    {
      "date": "2026-10-19",
      "rating": "Uncertain",
      "from": null,
      "rule_version": "1.6"
    }
  ],
  "versions": [
    {
      "version": "1.0",
      "date": "2026-10-24",
      "rating": "Uncertain",
      "change": "First published."
    }
  ],
  "research_desk": "https://knowyourprime.com/research-desk-blood-pressure#calibrated_change_tracking",
  "related_findings": [
    "https://knowyourprime.com/evidence-cuffless-blood-pressure-at-night",
    "https://knowyourprime.com/evidence-smartwatch-cuff-blood-pressure-accuracy"
  ],
  "related_articles": [
    "https://knowyourprime.com/can-a-smartwatch-measure-blood-pressure",
    "https://knowyourprime.com/how-accurate-is-samsung-watch-and-whoop-blood-pressure"
  ],
  "methodology": "https://knowyourprime.com/methodology",
  "citation": "KnowYourPrime Evidence Registry, Finding KYP-ER-0022, version 1.0, reviewed 2026-10-24. https://knowyourprime.com/evidence-calibrated-cuffless-blood-pressure-tracking"
}