Influence of Enhanced Administrative Case‐Finding Strategies on Prevalence of Hypertensive Disorders of Pregnancy in Ontario: A Population‐Based Descriptive Study

Figures

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  Figure 1. Major hypertensive disorders of pregnancy diagnoses by timing of diagnosis. Hypertensive disorders of pregnancy (HDP) are classified based on clinical symptoms (severity) and timing of onset. Chronic hypertension may be diagnosed before pregnancy or at <20 weeks gestation, while gestational hypertension and de novo preeclampsia (including eclampsia and hemolysis, elevated liver enzymes, low platelet count, HELLP syndrome) develop at ≥20 weeks gestation. HDP can resolve postpartum, persist beyond delivery, or be initially diagnosed in the postpartum period. *While eclampsia and HELLP syndrome are often considered to be severe manifestations of preeclampsia, they may also be classified as separate diagnoses. Preeclampsia is also frequently categorized based on severity (ie, preeclampsia with or without severe features). †Elevated blood pressure in most people diagnosed with de novo hypertension in pregnancy usually resolves within 6–12 weeks postpartum. However, depending on the severity of HDP, it may take up to a year for blood pressure to return to pre‐pregnancy levels and for other symptoms (eg, proteinuria) to fully resolve. 7 This figure was created in Biorender.com.

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  Figure 2. Classification strategies used to identify hypertensive disorders of pregnancy from Ontario health care administrative data sources. The severity hierarchy used in this study [least severe (1) to most severe (6)]: (1) unspecified maternal hypertension, (2) gestational hypertension, (3) chronic hypertension in pregnancy, (4) preeclampsia (includes Hemolysis, Elevated Liver enzymes, and Low Platelet count syndrome), (5) superimposed preeclampsia, (6) eclampsia (see Figure S5). This figure was created in Biorender.com.

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  Figure 3. Flow diagram summarizing subject eligibility and selection. This figure was created in Biorender.com.

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  Figure 4. Estimated overall prevalence of any HDP (per 1000 first deliveries) in Ontario from 2002 to 2017, stratified by case‐finding strategy and plurality. HDP = hypertensive disorders of pregnancy. See Tables S4 and S5 and Figures S3–S6 for further information about case‐finding strategies.

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  Figure 5. Bubble plots summarizing the prevalence (per 1000 deliveries) and prevalence ratios (reference: <20 years) of any hypertensive disorder of pregnancy across 5‐year age groups in subjects with a (A) singleton or (B) multiple gestation first delivery in Ontario, by case‐finding strategy. Estimates for subjects aged 20 to 40 years and 45 to 49 years (multiple gestation only) have been suppressed to reduce reidentification risk in compliance with ICES privacy policy. See Tables S4 and S5 and Figures S3–S6 for further information about case‐finding strategies.

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  Figure 6. Prevalence estimates (per 1000 deliveries) for 6 hypertensive disorders of pregnancy subtypes in subjects with a (A) singleton or (B) multiple gestation first delivery in Ontario from 2002 to 2017, stratified by case‐finding strategy. See Tables S4 and S5 and Figures S3–S6 for further information about case‐finding strategies.

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  Figure 7. Heat maps summarizing the estimated annual prevalence (per 1000 deliveries) of any hypertensive disorder of pregnancy in subjects with a (A) singleton or (B) multiple gestation first delivery in Ontario between 2002 and 2017, stratified by case‐finding strategy. See Tables S4 and S5 and Figures S3–S6 for further information about case‐finding strategies.

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  Figure 8. Line graphs summarizing annual prevalence estimates (per 1000 singleton deliveries) for gestational hypertension and preeclampsia in Ontario from 2002 to 2017 according to the (A) severity and (B) pre‐pregnancy hypertension + severity case‐finding strategies. See Tables S4 and S5 and Figures S3–S6 for further information about case‐finding strategies.