{"id":"d8277b2f-bf77-5288-a23d-8cfb288e4256","stable_key":"488ea171-36b8-5ef6-b5d3-98563980fdbf:hbot-amputation-reduction","predicate":"reduces","statement":"Major amputation occurred in 3 of 35 treated subjects (8.6%) versus 11 of 33 untreated (33.3%), a relative risk of 0.26, with the protective role confirmed on multivariate analysis.","claim_class":"observational","status":"source_derived_draft","evidence_grade":"ungraded","direction":"negative","is_public":true,"mechanism_event_id":"ac741e61-2ad1-5245-aabf-7d621ad42c3e","mechanism_event_label":"Fewer people in the treated group lost a limb in this trial.","subject":{"id":"581fa746-cb84-571b-87a0-4d461263f660","slug":"hyperbaric-oxygen","display_name":"Hyperbaric oxygen therapy","entity_type_key":"drug"},"object":{"id":"41ebf1bc-b4f3-5922-a4ba-b3e7de690fa2","slug":"major-amputation","display_name":"Major lower-limb amputation","entity_type_key":"cellular_process"},"evidence_count":1,"mechanism_event":{"id":"ac741e61-2ad1-5245-aabf-7d621ad42c3e","stable_key":"488ea171-36b8-5ef6-b5d3-98563980fdbf:hbot-amputation-reduction-event","event_type":"observed_intervention","label":"Fewer people in the treated group lost a limb in this trial.","description":"Major amputation occurred in 3 of 35 treated subjects (8.6%) versus 11 of 33 untreated (33.3%), a relative risk of 0.26, with the protective role confirmed on multivariate analysis.","status":"provisional","compartment":null,"participants":[{"entity":{"id":"581fa746-cb84-571b-87a0-4d461263f660","slug":"hyperbaric-oxygen","display_name":"Hyperbaric oxygen therapy","entity_type_key":"drug"},"role":"subject","stoichiometry":null,"state_label":"","sequence_order":0,"notes":""},{"entity":{"id":"41ebf1bc-b4f3-5922-a4ba-b3e7de690fa2","slug":"major-amputation","display_name":"Major lower-limb amputation","entity_type_key":"cellular_process"},"role":"target","stoichiometry":null,"state_label":"","sequence_order":1,"notes":""}]},"contexts":[{"dimension":"evidence_span","value_text":"{\"source_cache\": \"artifacts/hbot-research/8941460.abstract.txt\", \"locator\": \"Indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"2f2904fa77e07a14257977ef8ca30fc46ee5ada35e65be2cc6512161bd0b440e\", \"start_char\": 0, \"end_char\": 1910, \"text_sha256\": \"2f2904fa77e07a14257977ef8ca30fc46ee5ada35e65be2cc6512161bd0b440e\"}","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"experimental_model","value_text":"Randomised study of 70 people admitted with severe prevalently ischaemic diabetic foot ulcer","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"exposure","value_text":"Systemic hyperbaric oxygen, mean 38.8 sessions, added to a full treatment protocol","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"limitations","value_text":"A single-centre randomised study with amputation as the endpoint. Adjunctive to an aggressive protocol, so the effect is of the addition, not of hyperbaric oxygen alone.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"nutrient_topic","value_text":"Hyperbaric oxygen research collection; topical membership is not evidence of a direct clinical effect, and a therapeutic exposure is not a dietary intake.","comparator":null,"unit":null,"notes":"","entity":{"slug":"hyperbaric-oxygen","display_name":"Hyperbaric oxygen therapy","entity_type_key":"drug"}},{"dimension":"organism","value_text":"Human","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"plain_language","value_text":"Fewer people in the treated group lost a limb in this trial.","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"primary_references","value_text":"[hbot-p8941460] Adjunctive systemic hyperbaric oxygen therapy in treatment of severe prevalently ischemic diabetic foot ulcer. A randomized study. (1996). https://pubmed.ncbi.nlm.nih.gov/8941460/ DOI: 10.2337/diacare.19.12.1338","comparator":null,"unit":null,"notes":"","entity":null},{"dimension":"tissue_or_cell_type","value_text":"Foot","comparator":null,"unit":null,"notes":"","entity":null}],"evidence":[{"id":"6985340f-9324-5d6a-9146-60ea741e74b5","evidence_kind":"source_excerpt","locator":"Lines 114-125","start_line":114,"end_line":125,"excerpt":"### hbot-amputation-reduction\nMajor amputation occurred in 3 of 35 treated subjects (8.6%) versus 11 of 33 untreated (33.3%), a relative risk of 0.26, with the protective role confirmed on multivariate analysis.\nCondition category: normal\nnutrient_topic: Hyperbaric oxygen research collection; topical membership is not evidence of a direct clinical effect, and a therapeutic exposure is not a dietary intake.\nplain_language: Fewer people in the treated group lost a limb in this trial.\norganism: Human\ntissue_or_cell_type: Foot\nexperimental_model: Randomised study of 70 people admitted with severe prevalently ischaemic diabetic foot ulcer\nlimitations: A single-centre randomised study with amputation as the endpoint. Adjunctive to an aggressive protocol, so the effect is of the addition, not of hyperbaric oxygen alone.\nexposure: Systemic hyperbaric oxygen, mean 38.8 sessions, added to a full treatment protocol\nevidence_span: {\"source_cache\": \"artifacts/hbot-research/8941460.abstract.txt\", \"locator\": \"Indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"2f2904fa77e07a14257977ef8ca30fc46ee5ada35e65be2cc6512161bd0b440e\", \"start_char\": 0, \"end_char\": 1910, \"text_sha256\": \"2f2904fa77e07a14257977ef8ca30fc46ee5ada35e65be2cc6512161bd0b440e\"}\n[hbot-p8941460] Adjunctive systemic hyperbaric oxygen therapy in treatment of severe prevalently ischemic diabetic foot ulcer. A randomized study. (1996). https://pubmed.ncbi.nlm.nih.gov/8941460/ DOI: 10.2337/diacare.19.12.1338","model_system":"Randomised study of 70 people admitted with severe prevalently ischaemic diabetic foot ulcer","directness":"author_interpretation","verification_status":"source_derived_draft","notes":"Exact curation-document quotation, not publisher quotation. Study references: [hbot-p8941460] Adjunctive systemic hyperbaric oxygen therapy in treatment of severe prevalently ischemic diabetic foot ulcer. A randomized study. (1996). https://pubmed.ncbi.nlm.nih.gov/8941460/ DOI: 10.2337/diacare.19.12.1338","relationship":"supports","weight":1.0,"link_notes":"","source":{"id":"dbf39b48-c95e-5291-b404-349ffbc4488f","stable_key":"import-488ea171-36b8-5ef6-b5d3-98563980fdbf","title":"Hyperbaric oxygen: the exposure, its reactive species, the signals they carry, and the nutrient-dependent enzymes that handle them (2026-09-19)","document_type":"imported_text","citation_label":"AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text.","file_path":"","sha256":"fb2443321804010d82c6b96ab61cc51b4b6628ddbb15751cb0e90b491606e79c","revision_id":"bb699ea5-b492-5728-b22c-48f0842a8ac9","review_status":"unverified_draft","notes":""}}],"relations":[],"conflicts":[{"id":"f9f92bba-2388-5b54-a427-5e2938d16026","title":"Does hyperbaric oxygen help a diabetic foot ulcer, or not?","kind":"contradiction","status":"open","why":"A randomised study of severe prevalently ischaemic ulcers found major amputation cut from 33% to 9%, while a propensity-adjusted cohort of 6259 people in routine wound care found treated people less likely to heal and more likely to lose a limb. The populations differ sharply: the trial selected severe ischaemic ulcers with an aggressive inpatient protocol, the cohort covered anyone meeting reimbursement criteria. Observational treatment selection by severity pushes in the direction the cohort found, and the trial is small and single-centre. Neither study measured the other population, and the reason for the difference is not established here.","resolution":"Unresolved; needs review.","created_at":"2026-09-19 23:38:18","record_type":"conflict","display_label":"Recorded conflict","record_url":"/conflicts/f9f92bba-2388-5b54-a427-5e2938d16026","sides":[{"conflict_id":"f9f92bba-2388-5b54-a427-5e2938d16026","ordinal":0,"label":"Fewer people in the treated group lost a limb in this trial.","revision_id":"bb699ea5-b492-5728-b22c-48f0842a8ac9","start_line":114,"end_line":125,"quote":"### hbot-amputation-reduction\nMajor amputation occurred in 3 of 35 treated subjects (8.6%) versus 11 of 33 untreated (33.3%), a relative risk of 0.26, with the protective role confirmed on multivariate analysis.\nCondition category: normal\nnutrient_topic: Hyperbaric oxygen research collection; topical membership is not evidence of a direct clinical effect, and a therapeutic exposure is not a dietary intake.\nplain_language: Fewer people in the treated group lost a limb in this trial.\norganism: Human\ntissue_or_cell_type: Foot\nexperimental_model: Randomised study of 70 people admitted with severe prevalently ischaemic diabetic foot ulcer\nlimitations: A single-centre randomised study with amputation as the endpoint. Adjunctive to an aggressive protocol, so the effect is of the addition, not of hyperbaric oxygen alone.\nexposure: Systemic hyperbaric oxygen, mean 38.8 sessions, added to a full treatment protocol\nevidence_span: {\"source_cache\": \"artifacts/hbot-research/8941460.abstract.txt\", \"locator\": \"Indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"2f2904fa77e07a14257977ef8ca30fc46ee5ada35e65be2cc6512161bd0b440e\", \"start_char\": 0, \"end_char\": 1910, \"text_sha256\": \"2f2904fa77e07a14257977ef8ca30fc46ee5ada35e65be2cc6512161bd0b440e\"}\n[hbot-p8941460] Adjunctive systemic hyperbaric oxygen therapy in treatment of severe prevalently ischemic diabetic foot ulcer. A randomized study. (1996). https://pubmed.ncbi.nlm.nih.gov/8941460/ DOI: 10.2337/diacare.19.12.1338","source_key":"import-488ea171-36b8-5ef6-b5d3-98563980fdbf","source_title":"Hyperbaric oxygen: the exposure, its reactive species, the signals they carry, and the nutrient-dependent enzymes that handle them (2026-09-19)","claim_ids":["d8277b2f-bf77-5288-a23d-8cfb288e4256"]},{"conflict_id":"f9f92bba-2388-5b54-a427-5e2938d16026","ordinal":1,"label":"In routine care, the treated group did worse, not better.","revision_id":"bb699ea5-b492-5728-b22c-48f0842a8ac9","start_line":127,"end_line":138,"quote":"### hbot-cohort-no-benefit\nIn propensity-score-adjusted models, individuals receiving hyperbaric oxygen were less likely to have their foot ulcer heal (hazard ratio 0.68) and more likely to have an amputation (2.37), and additional analyses including an instrumental variable did not change the result.\nCondition category: normal\nnutrient_topic: Hyperbaric oxygen research collection; topical membership is not evidence of a direct clinical effect, and a therapeutic exposure is not a dietary intake.\nplain_language: In routine care, the treated group did worse, not better.\norganism: Human\ntissue_or_cell_type: Foot\nexperimental_model: Longitudinal observational cohort of 6259 people in a wound care network, propensity-score adjusted\nlimitations: A large observational cohort, not a randomised trial. Propensity scores and an instrumental variable were used, but treatment selection by severity cannot be fully excluded; the direction of the result is opposite to the randomised study recorded alongside it.\nexposure: Hyperbaric oxygen as delivered under Medicare eligibility criteria\nevidence_span: {\"source_cache\": \"artifacts/hbot-research/23423696.abstract.txt\", \"locator\": \"Indexed abstract; zero-based, end-exclusive Unicode character offsets\", \"file_sha256\": \"2129b8a0c7356a65fbcedf4032e381f7dc22548282f894b785504f067fa6ced4\", \"start_char\": 0, \"end_char\": 1491, \"text_sha256\": \"2129b8a0c7356a65fbcedf4032e381f7dc22548282f894b785504f067fa6ced4\"}\n[hbot-p23423696] Lack of effectiveness of hyperbaric oxygen therapy for the treatment of diabetic foot ulcer and the prevention of amputation: a cohort study. (2013). https://pubmed.ncbi.nlm.nih.gov/23423696/ DOI: 10.2337/dc12-2160","source_key":"import-488ea171-36b8-5ef6-b5d3-98563980fdbf","source_title":"Hyperbaric oxygen: the exposure, its reactive species, the signals they carry, and the nutrient-dependent enzymes that handle them (2026-09-19)","claim_ids":["6887ce75-3ce0-5521-a673-df42aa3cc9e2"]}]}],"corrections":[],"research":null}