Impact of low-dose CT screening for lung cancer on ethnic health inequities in New Zealand: a cost-effectiveness analysis

OBJECTIVE

There are large inequities in the lung cancer burden for the Indigenous Māori population of New Zealand. We model the potential lifetime health gains, equity impacts and cost-effectiveness of a national low-dose CT (LDCT) screening programme for lung cancer in smokers aged 55-74 years with a 30 pack-year history, and for formers smokers who have quit within the last 15 years.

DESIGN

A Markov macrosimulation model estimated: health benefits (health-adjusted life-years (HALYs)), costs and cost-effectiveness of biennial LDCT screening. Input parameters came from literature and NZ-linked health datasets.

SETTING

New Zealand.

PARTICIPANTS

Population aged 55-74 years in 2011.

INTERVENTIONS

Biennial LDCT screening for lung cancer compared with usual care.

OUTCOME MEASURES

Incremental cost-effectiveness ratios were calculated using the average difference in costs and HALYs between the screened and the unscreened populations. Equity analyses included substituting non-Māori values for Māori values of background morbidity, mortality and stage-specific survival. Changes in inequities in lung cancer survival and 'health-adjusted life expectancy' (HALE) were measured.

RESULTS

LDCT screening in NZ is likely to be cost-effective for the total population: NZ$34 400 per HALY gained (95% uncertainty interval NZ$27 500 to NZ$42 900) and for Māori separately (using a threshold of gross domestic product per capita NZ$45 000). Health gains per capita for Māori females were twice that for non-Māori females and 25% greater for Māori males compared with non-Māori males. LDCT screening will narrow absolute inequities in HALE and lung cancer mortality for Māori, but will slightly increase relative inequities in mortality from lung cancer (compared with non-Māori) due to differential stage-specific survival.

CONCLUSION

A national biennial LDCT lung cancer screening programme in New Zealand is likely to be cost-effective, will improve total population health and reduce health inequities for Māori. Attention must be paid to addressing ethnic inequities in stage-specific lung cancer survival.

Diagnostic properties of differing BP thresholds for adverse pregnancy outcomes in standard-risk nulliparous women: A secondary analysis of SCOPE cohort data

BACKGROUND

In 2017, the American College of Cardiology and American Heart Association (ACC/AHA) lowered blood pressure (BP) thresholds to define hypertension in adults outside pregnancy. If used in pregnancy, these lower thresholds may identify women at increased risk of adverse outcomes, which would be particularly useful to risk-stratify nulliparous women. In this secondary analysis of the SCOPE cohort, we asked whether, among standard-risk nulliparous women, the ACC/AHA BP categories could identify women at increased risk for adverse outcomes.

METHODS AND FINDINGS

Included were pregnancies in the international SCOPE cohort with birth at ≥20 weeks' gestation, 2004 to 2008. Women were mostly of white ethnicity, in their 20s, and of normal-to-overweight body mass index (BMI). Excluded were pregnancies ending in fetal loss at <20 weeks' gestation, and those terminated at any point in pregnancy. Women were categorized by highest BP during pregnancy, using ACC/AHA criteria: normal (BP <120/80 mmHg), "Elevated BP" (BP 120 to 129 mmHg/<80 mmHg), "Stage-1 hypertension" (systolic BP [sBP] 130 to 139 mmHg or diastolic BP [dBP] 80 to 89 mmHg), and "Stage-2 hypertension" that was non-severe (sBP 140 to 159 mmHg or dBP 90 to 109 mmHg) or severe (sBP ≥160 mmHg or dBP ≥110 mmHg). Primary outcomes were preterm birth (PTB), low birthweight, postpartum hemorrhage, and neonatal care admission. Adjusted relative risks (aRRs) and diagnostic test properties were calculated for each outcome, according to: each BP category (versus "normal"), and using the lower limit of each BP category as a cut-off. RRs were adjusted for maternal age, BMI, smoking, ethnicity, and alcohol use. Of 5,628 women in SCOPE, 5,597 were included in this analysis. When compared with normotension, severe "Stage 2 hypertension" was associated with PTB (24.0% versus 5.3%; aRR 4.88, 95% confidence interval, CI [3.46 to 6.88]), birthweight <10th centile (24.4% versus 8.8%; aRR 2.70 [2.00 to 3.65]), and neonatal unit admission (32.9% versus 8.9%; aRR 3.40 [2.59 to 4.46]). When compared with normotension, non-severe "Stage 2 hypertension" was associated with birthweight <10th centile (16.1% versus 8.8%; aRR 1.82 [1.45 to 2.29]) and neonatal unit admission (15.4% versus 8.9%; aRR 1.65 [1.31 to 2.07]), but no association with adverse outcomes was seen with BP categories below "Stage 2 hypertension." When each BP category was assessed as a threshold for diagnosis of abnormal BP (compared with BP values below), only severe "Stage 2 hypertension" had a useful (good) likelihood ratio (LR) of 5.09 (95% CI [3.84 to 6.75]) for PTB. No BP threshold could rule-out adverse outcomes (i.e., had a negative LR <0.2). Limitations of our analysis include lack of ethnic diversity and use of values from clinical notes for BP within 2 weeks before birth. This study was limited by: its retrospective nature, not all women having BP recorded at all visits, and the lack of detail about some outcomes.

CONCLUSIONS

In this study, we observed that 2017 ACC/AHA BP categories demonstrated a similar pattern of association and diagnostic test properties in nulliparous women, as seen in the general obstetric population. BP thresholds below the currently used "Stage 2 hypertension" were not associated with PTB, low birthweight, postpartum hemorrhage, or neonatal unit admission. This study does not support implementation of lower BP values as abnormal in nulliparous pregnant women.