Table 1.

Examples of regression discontinuity designs in clinical, prevention and public health, and health policy studies

Studies	Exposures	Type of assignment variables	Threshold rules	Outcomes
Clinical:
Bor et al 2014, 20157 16	HIV antiretroviral therapy	Therapeutic	Patients with CD4 counts <200 cells/mm3 eligible to initiate early antiretroviral treatment in South Africa	Mortality, immune recovery, retention in clinical care
Almond et al 201013	Neonatal intensive care	Therapeutic	Infants with birth weights <1500 g (designated very low birth weight) recommended for intensive care in United States	Infant mortality
Bharadwaj et al 201314	Neonatal intensive care	Therapeutic	Infants with birth weights <1500 g (designated very low birth weight) recommended for intensive care in Chile and Norway	Child cognitive development, academic achievement
Geneletti et al 201515	Statins	Therapeutic	10 year cardiovascular risk >20% as a guideline to initiate statins	Low density lipoprotein cholesterol
Jensen and Wust 201519	Caesarean section	Calendar time	Changes in information and guidelines about efficacy of caesarean section starting 21 October 2000 in Denmark	Apgar score, physician visits, hospital admissions for neonates
Prevention and public health:
Smith et al 201520	HPV vaccine	Calendar time	Vaccines were available for select age groups after 1 January 1994	Cervical dysplasia and anogenital warts
Callaghan 201321	Minimum drinking age	Age	Adults aged 21 or older can legally purchase and consume alcohol in United States	Mortality
Ludwig and Miller 200722	Head Start program	Program eligibility	Counties ranked <300 based on historic poverty rates were eligible to receive federal Head Start	Child mortality
Chen et al 201323	Air pollution	Geographic	Households north of China’s Huai River received subsidies for high emission coal to heat homes	Mortality
Health policy:
De La Mata et al 201224	Health insurance	Program eligibility	People in households below a specific income threshold were eligible for Medicaid	Healthcare utilization among children
Wherry et al 201525	Health insurance	Calendar time	People born after 1 October 1983 were eligible for more years of Medicaid coverage owing to rule changes	Hospital admissions among adolescents
Sood et al 201426	Health insurance	Geographic	People living in predesignated districts were eligible to receive insurance, whereas those in neighboring districts were not	Mortality
Almond et al 201127	Length of hospital stay	Clock time	Patients admitted after 12 am were allowed longer hospital stays based on insurance rules	Maternal and newborn health