{
  "release_id": "15708f235d73cd42",
  "id": "maternal:chap-trial",
  "owner": "maternal",
  "kind": "study",
  "slug": "chap-trial",
  "name": "CHAP (Chronic Hypertension and Pregnancy) trial",
  "aliases": [
    "CHAP"
  ],
  "atlases": [
    "maternal"
  ],
  "summary_plain": "A large trial in the United States that asked whether women with mildly raised blood pressure before or early in pregnancy do better if they take blood pressure medicine to keep their pressure under 140/90, or if they take medicine only when their pressure becomes severe. Everyone knew which approach they were in.",
  "summary_technical": "Pragmatic, open-label, randomized trial (NCT02299414; phase 4 in the registry). 2408 women were enrolled (the Results text reports 2419 randomized and 2408 analysed). Primary outcome: a composite of pre-eclampsia with severe features, medically indicated preterm birth before 35 weeks, placental abruption, or fetal or neonatal death. Primary safety outcome: a birth weight under the 10th percentile for the baby’s gestational age (small for gestational age). The funder was the National Heart, Lung, and Blood Institute; the registry names the University of Alabama at Birmingham as lead sponsor (no record in this atlas yet). The registry start date (2015-06) and the manuscript’s screening period (from September 2015) differ; the registry date is the one recorded.",
  "editorial_state": "draft",
  "last_substantive_edit": "2026-10-11",
  "last_evidence_check": null,
  "next_review_due": null,
  "external_ids": [
    {
      "namespace": "nct",
      "value": "NCT02299414"
    }
  ],
  "navigation": {
    "maternal": {
      "life-stage": [
        "pregnancy",
        "newborn"
      ]
    }
  },
  "payload": {
    "design": "Pragmatic, multicenter, open-label, randomized controlled trial in the United States. Women were randomly assigned either to treatment aimed at keeping blood pressure under 140/90 mm Hg (the active group) or to standard care, in which blood-pressure drugs were not given, or were stopped if already in use, unless severe hypertension appeared. The sample size was reduced from a planned 4700 to a final 2404; the monitoring board for data and safety agreed to the reduction. A blinded outcome adjudication committee reviewed suspected primary and selected secondary outcomes. Follow-up ran to 6 weeks after birth.",
    "drug_phase": "4",
    "registry_statuses": [
      {
        "status": "COMPLETED",
        "snapshot": "maternal:ctgov-nct02299414-2026-10-11"
      }
    ],
    "start_date": {
      "date": "2015-06",
      "type": "actual",
      "snapshot": "maternal:ctgov-nct02299414-2026-10-11"
    },
    "primary_completion_date": {
      "date": "2022-04-01",
      "type": "actual",
      "snapshot": "maternal:ctgov-nct02299414-2026-10-11"
    },
    "completion_date": {
      "date": "2022-12-16",
      "type": "actual",
      "snapshot": "maternal:ctgov-nct02299414-2026-10-11"
    },
    "countries": [
      {
        "code": "US",
        "snapshot": "maternal:ctgov-nct02299414-2026-10-11"
      }
    ],
    "care_setting": {
      "description": "Recruiting sites of the CHAP Trial Consortium in the United States (more than 70 per the Methods; 2419 women were randomized at 61 sites per the Results). The manuscript does not say whether the sites were clinics or hospitals.",
      "snapshot": "maternal:pmc-pmc9575330-2026-10-11"
    },
    "stopped_early": null,
    "enrollment": [
      {
        "count": 2408,
        "basis": "enrolled",
        "unit": "women",
        "snapshot": "maternal:pubmed-35363951-2026-10-11"
      },
      {
        "count": 2408,
        "basis": "enrolled",
        "unit": "women (registry enrollment, type ACTUAL)",
        "snapshot": "maternal:ctgov-nct02299414-2026-10-11"
      },
      {
        "count": 2419,
        "basis": "randomized",
        "unit": "women",
        "snapshot": "maternal:pmc-pmc9575330-2026-10-11"
      },
      {
        "count": 2404,
        "basis": "planned",
        "unit": "women (final sample size approved by the data and safety monitoring board)",
        "snapshot": "maternal:pmc-pmc9575330-2026-10-11"
      },
      {
        "count": 4700,
        "basis": "planned",
        "unit": "women (originally planned enrollment)",
        "snapshot": "maternal:pmc-pmc9575330-2026-10-11"
      }
    ],
    "arms": [
      {
        "id": "maternal:chap-trial-arm-active",
        "label": "Active treatment to a goal below 140/90 mm Hg",
        "intervention": "maternal:antihypertensive-treatment-non-severe-hypertension-pregnancy",
        "description": "Antihypertensive drugs started or continued to reach a blood-pressure goal below 140/90 mm Hg. The first-line drugs were labetalol or extended-release nifedipine, supplied by the trial investigators."
      },
      {
        "id": "maternal:chap-trial-arm-control",
        "label": "Standard (control) treatment",
        "intervention": null,
        "description": "No antihypertensive treatment unless severe hypertension developed (systolic 160 mm Hg or higher, or diastolic 105 mm Hg or higher). Treatment already under way was withheld or stopped at randomization."
      }
    ],
    "findings": [
      {
        "id": "maternal:f-chap-primary-active",
        "outcome_id": "maternal:outcome-chap-primary-composite",
        "context_id": "maternal:ctx-chap-pregnancies-composite",
        "arm_id": "maternal:chap-trial-arm-active",
        "comparator_arm_id": null,
        "claim_id": "maternal:claim-chap-primary-composite",
        "snapshot_id": "maternal:pmc-pmc9575330-2026-10-11",
        "endpoint_role": "primary",
        "effect_measure": "women with a primary-outcome event (count), complete-case analysis",
        "numeric_value": 353,
        "reported_text": "353/1170 (30.2%)",
        "unit": "women",
        "denominator": 1170,
        "denominator_status": null,
        "denominator_basis": "Complete-case analysis: women with sufficient data on the primary outcome (Table 2 footnote). 1208 women were assigned to the treated group and 1200 to the control group.",
        "time_window": "No single period is stated for the composite. Pre-eclampsia up to 2 weeks after birth; fetal or neonatal death at under 28 days (Table 2 row label). The registry gives up to 90 days for neonatal death.",
        "estimate_lower": null,
        "estimate_upper": null,
        "interval_method": null,
        "interval_status": "not_applicable"
      },
      {
        "id": "maternal:f-chap-primary-control",
        "outcome_id": "maternal:outcome-chap-primary-composite",
        "context_id": "maternal:ctx-chap-pregnancies-composite",
        "arm_id": "maternal:chap-trial-arm-control",
        "comparator_arm_id": null,
        "claim_id": "maternal:claim-chap-primary-composite",
        "snapshot_id": "maternal:pmc-pmc9575330-2026-10-11",
        "endpoint_role": "primary",
        "effect_measure": "women with a primary-outcome event (count), complete-case analysis",
        "numeric_value": 427,
        "reported_text": "427/1155 (37.0%)",
        "unit": "women",
        "denominator": 1155,
        "denominator_status": null,
        "denominator_basis": "Complete-case analysis: women with sufficient data on the primary outcome (Table 2 footnote). 1208 women were assigned to the treated group and 1200 to the control group.",
        "time_window": "No single period is stated for the composite. Pre-eclampsia up to 2 weeks after birth; fetal or neonatal death at under 28 days (Table 2 row label). The registry gives up to 90 days for neonatal death.",
        "estimate_lower": null,
        "estimate_upper": null,
        "interval_method": null,
        "interval_status": "not_applicable"
      },
      {
        "id": "maternal:f-chap-primary-arr",
        "outcome_id": "maternal:outcome-chap-primary-composite",
        "context_id": "maternal:ctx-chap-pregnancies-composite",
        "arm_id": "maternal:chap-trial-arm-active",
        "comparator_arm_id": "maternal:chap-trial-arm-control",
        "claim_id": "maternal:claim-chap-primary-composite",
        "snapshot_id": "maternal:pmc-pmc9575330-2026-10-11",
        "endpoint_role": "primary",
        "effect_measure": "adjusted risk ratio, active treatment vs control (multiple imputation analysis with multivariable log-binomial regression, N = 2408; Table 2 footnote)",
        "numeric_value": 0.82,
        "reported_text": "0.82 (0.74-0.92), P<0.001",
        "unit": "ratio",
        "denominator": null,
        "denominator_status": "not_applicable",
        "denominator_basis": "Imputation analysis of all 2408 women analysed, not the complete-case counts above (Table 2 headings)",
        "time_window": "No single period is stated for the composite. Pre-eclampsia up to 2 weeks after birth; fetal or neonatal death at under 28 days (Table 2 row label). The registry gives up to 90 days for neonatal death.",
        "estimate_lower": 0.74,
        "estimate_upper": 0.92,
        "interval_method": "95% confidence interval",
        "interval_status": null
      },
      {
        "id": "maternal:f-chap-sga10-active",
        "outcome_id": "maternal:outcome-chap-sga-below-10th-percentile",
        "context_id": "maternal:ctx-chap-newborns-sga",
        "arm_id": "maternal:chap-trial-arm-active",
        "comparator_arm_id": null,
        "claim_id": "maternal:claim-chap-sga-safety",
        "snapshot_id": "maternal:pmc-pmc9575330-2026-10-11",
        "endpoint_role": "primary",
        "effect_measure": "infants with birth weight below the 10th percentile (count), complete-case analysis",
        "numeric_value": 128,
        "reported_text": "128/1146 (11.2%)",
        "unit": "infants",
        "denominator": 1146,
        "denominator_status": null,
        "denominator_basis": "Complete-case analysis: infants with sufficient birth-weight data (Table 2 footnote). 1208 women were assigned to the treated group and 1200 to the control group.",
        "time_window": "Birth",
        "estimate_lower": null,
        "estimate_upper": null,
        "interval_method": null,
        "interval_status": "not_applicable"
      },
      {
        "id": "maternal:f-chap-sga10-control",
        "outcome_id": "maternal:outcome-chap-sga-below-10th-percentile",
        "context_id": "maternal:ctx-chap-newborns-sga",
        "arm_id": "maternal:chap-trial-arm-control",
        "comparator_arm_id": null,
        "claim_id": "maternal:claim-chap-sga-safety",
        "snapshot_id": "maternal:pmc-pmc9575330-2026-10-11",
        "endpoint_role": "primary",
        "effect_measure": "infants with birth weight below the 10th percentile (count), complete-case analysis",
        "numeric_value": 117,
        "reported_text": "117/1124 (10.4%)",
        "unit": "infants",
        "denominator": 1124,
        "denominator_status": null,
        "denominator_basis": "Complete-case analysis: infants with sufficient birth-weight data (Table 2 footnote). 1208 women were assigned to the treated group and 1200 to the control group.",
        "time_window": "Birth",
        "estimate_lower": null,
        "estimate_upper": null,
        "interval_method": null,
        "interval_status": "not_applicable"
      },
      {
        "id": "maternal:f-chap-sga10-arr",
        "outcome_id": "maternal:outcome-chap-sga-below-10th-percentile",
        "context_id": "maternal:ctx-chap-newborns-sga",
        "arm_id": "maternal:chap-trial-arm-active",
        "comparator_arm_id": "maternal:chap-trial-arm-control",
        "claim_id": "maternal:claim-chap-sga-safety",
        "snapshot_id": "maternal:pmc-pmc9575330-2026-10-11",
        "endpoint_role": "primary",
        "effect_measure": "adjusted risk ratio, active treatment vs control (multiple imputation analysis with multivariable log-binomial regression, N = 2408; Table 2 footnote)",
        "numeric_value": 1.04,
        "reported_text": "1.04 (0.82-1.31), P = 0.76",
        "unit": "ratio",
        "denominator": null,
        "denominator_status": "not_applicable",
        "denominator_basis": "Imputation analysis of all 2408 patients (Table 2, N = 2408), not the complete-case counts above (Table 2 headings)",
        "time_window": "Birth",
        "estimate_lower": 0.82,
        "estimate_upper": 1.31,
        "interval_method": "95% confidence interval",
        "interval_status": null
      },
      {
        "id": "maternal:f-chap-preeclampsia-active",
        "outcome_id": "maternal:outcome-chap-any-preeclampsia",
        "context_id": "maternal:ctx-chap-women-mild-chronic-htn-singleton-lt23w",
        "arm_id": "maternal:chap-trial-arm-active",
        "comparator_arm_id": null,
        "claim_id": "maternal:claim-chap-any-preeclampsia",
        "snapshot_id": "maternal:pmc-pmc9575330-2026-10-11",
        "endpoint_role": "secondary",
        "effect_measure": "women with any pre-eclampsia (count)",
        "numeric_value": 295,
        "reported_text": "295 (24.4%)",
        "unit": "women",
        "denominator": 1208,
        "denominator_status": null,
        "denominator_basis": "All women assigned to the treated group (Table 3 column heading, N = 1208).",
        "time_window": "Not stated for this outcome in the manuscript text",
        "estimate_lower": null,
        "estimate_upper": null,
        "interval_method": null,
        "interval_status": "not_applicable"
      },
      {
        "id": "maternal:f-chap-preeclampsia-control",
        "outcome_id": "maternal:outcome-chap-any-preeclampsia",
        "context_id": "maternal:ctx-chap-women-mild-chronic-htn-singleton-lt23w",
        "arm_id": "maternal:chap-trial-arm-control",
        "comparator_arm_id": null,
        "claim_id": "maternal:claim-chap-any-preeclampsia",
        "snapshot_id": "maternal:pmc-pmc9575330-2026-10-11",
        "endpoint_role": "secondary",
        "effect_measure": "women with any pre-eclampsia (count)",
        "numeric_value": 373,
        "reported_text": "373 (31.1%)",
        "unit": "women",
        "denominator": 1200,
        "denominator_status": null,
        "denominator_basis": "All women assigned to the control group (Table 3 column heading, N = 1200).",
        "time_window": "Not stated for this outcome in the manuscript text",
        "estimate_lower": null,
        "estimate_upper": null,
        "interval_method": null,
        "interval_status": "not_applicable"
      },
      {
        "id": "maternal:f-chap-preeclampsia-rr",
        "outcome_id": "maternal:outcome-chap-any-preeclampsia",
        "context_id": "maternal:ctx-chap-women-mild-chronic-htn-singleton-lt23w",
        "arm_id": "maternal:chap-trial-arm-active",
        "comparator_arm_id": "maternal:chap-trial-arm-control",
        "claim_id": "maternal:claim-chap-any-preeclampsia",
        "snapshot_id": "maternal:pmc-pmc9575330-2026-10-11",
        "endpoint_role": "secondary",
        "effect_measure": "risk ratio, active treatment vs control (Table 3 treatment effect; the table footnote says it is a risk ratio and the abstract does not call it adjusted)",
        "numeric_value": 0.79,
        "reported_text": "0.79 (0.69 to 0.89)",
        "unit": "ratio",
        "denominator": null,
        "denominator_status": "not_applicable",
        "denominator_basis": "Comparison of the two per-arm rows above",
        "time_window": "Not stated for this outcome in the manuscript text",
        "estimate_lower": 0.69,
        "estimate_upper": 0.89,
        "interval_method": "95% confidence interval",
        "interval_status": null
      }
    ]
  },
  "content_digest": "55158f7ec3a5ca54f0f81cf6128a216380fe98ed5335083a98cbddfc01626c57",
  "review": {
    "content_digest": "55158f7ec3a5ca54f0f81cf6128a216380fe98ed5335083a98cbddfc01626c57",
    "current": [],
    "conflicting": [],
    "stale": [],
    "inactive": []
  },
  "claims": [],
  "decisions": [],
  "relationships": {
    "outgoing": [
      {
        "predicate": "investigates",
        "label": "Tests a blood-pressure goal below 140/90 mm Hg against treating only severe hypertension",
        "clinical_claim_not_fact": false,
        "other_entity_id": "maternal:antihypertensive-treatment-non-severe-hypertension-pregnancy",
        "other_entity_in_atlas": true,
        "claim_id": null
      },
      {
        "predicate": "investigates",
        "label": "Enrolled women with mild chronic hypertension",
        "clinical_claim_not_fact": false,
        "other_entity_id": "maternal:chronic-hypertension-in-pregnancy",
        "other_entity_in_atlas": true,
        "claim_id": null
      },
      {
        "predicate": "investigates",
        "label": "Pre-eclampsia is part of the primary composite and a secondary outcome",
        "clinical_claim_not_fact": false,
        "other_entity_id": "maternal:preeclampsia",
        "other_entity_in_atlas": true,
        "claim_id": null
      },
      {
        "predicate": "funded_by",
        "label": "Funder (abstract funding statement)",
        "clinical_claim_not_fact": false,
        "other_entity_id": "maternal:nhlbi",
        "other_entity_in_atlas": true,
        "claim_id": null
      },
      {
        "predicate": "results_reported_in",
        "label": "Primary results, NEJM 2022",
        "clinical_claim_not_fact": false,
        "other_entity_id": "maternal:pub-chap-nejm-2022",
        "other_entity_in_atlas": true,
        "claim_id": null
      }
    ],
    "incoming": []
  },
  "page_path": "studies/chap-trial/",
  "context_path": "api/v1/context/maternal--chap-trial.md"
}