Skip to main content
. 2010 Feb 23;39(3):718–732. doi: 10.1093/ije/dyp378

Table 1.

Select characteristics of studies included in the meta-analyses of day-care attendance and childhood leukemia

Author, year (location) Case ascertainment Control selection Data collection Select results Confounding addressed
Petridou et al., 199323 (Greece, Attica and Crete)

  • 125 leukaemia (Attica) 11 leukaemia (Crete)

  • Age 0–14 years

  • Children’s hospitals of the University of Athens (1987–91) and the University of Crete (1990–92)

 187 frequency matched children who attended the outpatient clinic of the hospitals where the children with leukaemia were treated Telephone interviews with parents of children Attendance at crèche (yes/no)

  • At any time Leukaemia: 0.67 (0.41, 1.11)

  • In infancy (for ≥3 months in the first 2 years of life) Leukaemia: 0.28 (0.09, 0.88)

  • Frequency match: sex, age, hospital

  • Adjustment: place of residence, social class
Roman et al., 199440 (UK)

  • 38 ALL

  • Age 0–4 years

  • Diagnosed 1972–89

  • Born in west Berkshire or north Hampshire, and were residents there when diagnosed

 112 individually matched children selected from hospital delivery registers Parents were interviewed Preschool playgroup (yes/no)

  • In the year before diagnosis (for ≥3 months) ALL: 0.6 (0.2, 1.8)

  • Individual match: sex, date of birth, mother’s age, area of residence at birth, time of diagnosis

  • Adjustment: not specified
Petridou et al., 199724 (Greece)

  • 153 leukaemia

  • Age 0–14 years

  • Diagnosed 1993–94

  • Nation wide network of paediatric haematologists/oncologists

 300 individually matched children hospitalized at the same time as the corresponding case for acute conditions Guardians of all subjects completed an interviewer-administered questionnaire Day-care attendance (ever/never) Leukaemia: 0.83 (0.51, 1.37)

  • Individual match: sex, age, geographic region

  • Adjustment: maternal age at birth, maternal education, sibship size, birth order, persons per room
Schuz et al., 199942 (Germany)

  • 1010 AL (686 c-ALL)

  • Diagnosed 1980–94

  • Age 0–14 years

  • Nation wide German Children’s Cancer Registry at the University of Mainz

 2588 matched children randomly selected from complete files of local offices of registration of residents

  • Structured questionnaire based on the US Children’s Cancer Group

  • Day-care attendance not directly assessed

 Deficit in social contacts (yes/no, age ≤18 months excluded) AL: 1.1 (0.9, 1.3) c-ALL: 1.0 (0.8, 1.2) Analysis of AL

  • Individual match: date of birth, sex, district

  • Adjustment: SES

Analysis of c-ALL

  • Adjustment: sex, age, year of birth, study setting

  • Adjustment: SES, urbanization
Dockerty et al., 199922 (New Zealand)

  • 97 ALL

  • Diagnosed 1990–93

  • Age 0–14 years

  • New Zealand Cancer registry, public hospital admission/discharge computer system, and the Children’s Cancer Registry. Nationwide

  • 97 individually matched children randomly selected from the New Zealand born and resident childhood population using national birth records

  • 209 solid cancer cases

 Mothers interviewed in their homes using a questionnaire adapted from Patricia McKinney and Eve Roman in the UK Regular contact with other children from outside home at <12 months (yes/no, age <15 months excluded) ALL: 0.65 (0.36, 1.17)

  • Individual match: age and sex

  • Adjustment: sex, age, several others including social class
Infante-Rivard et al., 200034 (Canada)

  • 491 ALL

  • Diagnosed 1980–93

  • Age 0–9 years

  • Tertiary care centre similar to population-based ascertainment

 491 individually matched children chosen from the most complete census of children for the study years Structured questionnaire administered to mothers by phone Day-care attendance by age at entry

  • Entry ≤2 years old vs no ALL: 0.49 (0.31, 0.77)

  • Entry at >2 years old vs no ALL: 0.67 (0.45, 1.01)

  • Individual match: age, sex, region of residence at diagnosis

  • Adjustment: maternal age, maternal education
Neglia et al., 200038 (USA)

  • 1744 ALL (633 c-ALL; excludes cases < 1 year)

  • Diagnosed 1989–93

  • Age 0–14 years

  • Children’s Cancer Group member institutions throughout the USA

 1879 individually matched children randomly selected using the random digit dialing (RDD) methodology Structured interview Day-care attendance (age <1 year excluded)

  • Yes vs no ALL: 0.96 (0.82, 1.12) c-ALL: 0.96 (0.75, 1.24)

  • Day care before age 2 vs no ALL: 0.99 (0.84, 1.17) c-ALL: 1.05 (0.80, 1.37)

  • Individual match: age, race, telephone area code, exchange, sex (T-cell leukaemia only)

  • Adjustment: maternal race, education, family income
Rosenbaum et al., 200041 (USA)

  • 255 ALL

  • Diagnosed 1980–91

  • Age 0–14 years

  • Four clinical centers in a 31-county study region. Institutional tumour registries and department of paediatric haematology–oncology records

 760 frequency matched children randomly selected through the Live Birth Certificate Registry maintained by the New York State Department of Health Self-administered questionnaire mailed to the parents of subjects Total duration of out-of-home care (duration vs >36 months) ALL: Stay home: 1.32 (0.70, 2.52) 1–18 months: 1.74 (0.89, 3.42) 19–36 months: 1.32 (0.70, 2.52)

  • Frequency match: sex, age, race, birth year

  • Adjustment: maternal age, maternal education, birth year, maternal employment, breastfeeding, birth order
Chan et al., 200232 (Hong Kong)

  • 98 AL (66 c-ALL)

  • Diagnosed 1994–97

  • Age 2–14 years

  • Hong Kong Pediatric Hematology and Oncology Study Group

 228 children selected using RDD methodology In-person interview using a structured questionnaire adapted from UKCCS and translated into Chinese Index and family day-care attendance (3-category variable)

  • First year of life AL: 0.96 (0.70, 1.32) Child peak: 0.63 (0.38, 1.07) c-ALL: 0.93 (0.63, 1.36)

  • Matching: None

  • Adjustment: age, number of children in household at reference date
Perrillat et al., 200239 (France)

  • 280 AL (240 ALL)

  • Diagnosed 1995–99

  • Age 0–15 years

  • Hospitals of Lille, Lyon, Nancy and Paris. Cases need to have resided in the hospital catchment area

 288 frequency matched children hospitalized in the same hospital as the cases, and residing in the catchment area of the hospital In-person standardized questionnaire Day-care attendance (age <2 years excluded)

  • Ever vs never AL: 0.6 (0.4, 1.0)

  • Age started vs no day care >12 months: 0.5 (0.3, 1.0) 7–12 months: 0.6 (0.2, 1.7) ≤6 months: 0.5 (0.3, 1.0)

  • Frequency match: age, sex, hospital, hospital catchment area, ethnic origin

  • Adjustment: age, sex, hospital, ethnic origin, maternal education, parental professional category
Jourdan-Da Silva et al., 200435 (France)

  • 473 AL (408 ALL, 304 c-ALL)

  • Diagnosed 1995–98

  • Age 0–14 years

  • National Registry of Childhood Leukaemia and Lymphoma (NRCL)

 567 frequency matched children randomly selected using age, sex, and region quotas from a sample of 30 000 phone numbers representative of the French population on area of residence and municipality size Standardized self-administered questionnaire on mothers Day-care attendance (age <1 year excluded)

  • Ever vs never ALL: 0.7 (0.6, 1.0) c-ALL: 0.8 (0.6, 1.0)

  • Started at age <3 months vs never ALL: 0.6 (0.4, 0.8) c-ALL: 0.6 (0.4, 0.9)

  • Frequency match: age, sex, region

  • Adjustment: age, sex, region
Gilham et al., 200533 (UK)

  • 1286 ALL (791 c-ALL; excludes cases <2 years)

  • Diagnosed 1991–96

  • Age 0–14 years

  • Nation-wide ascertainment through pediatric oncology units

 6238 individually matched children randomly selected from primary care population registers In-person interview with parents using a structured questionnaire Social activity in the first year of life (age <2 years excluded)

  • Any vs no social activity ALL: 0.66 (0.56, 0.77) c-ALL: 0.67 (0.55, 0.82)

  • Age started vs no day care ALL- < 3 months: 0.71 (0.60, 0.85) 3–5 months: 0.71 (0.56, 0.90) 6–11 months: 0.76 (0.63, 0.92)

  • Individual match: sex, month and year of birth, region of residence at diagnosis

  • Adjustment: age at diagnosis, sex, region, maternal age, mother working at time of birth, deprivation
Ma et al., 200537 (USA)

  • 294 ALL (145 c-ALL; excludes case <1 year)

  • Diagnosed 1995–2002

  • Age 0–14 years

  • Population-based ascertainment from major paediatric clinical centres in Northern and Central California

 376 individually matched children randomly selected from statewide birth certificate files maintained by the California Department of Health Services Personal interview with primary caretaker Child-hours of exposure at day care (age <1 year excluded)

  • ≥5000 child-hours (1st year) vs 0 ALL- Hispanic: 2.10 (0.70, 6.34) White: 0.42 (0.18, 0.99) c-ALL- Hispanic: 2.53 (0.60, 10.7) White: 0.33 (0.11, 1.01)

  • Individual match: date of birth, sex, mother’s race, Hispanic status

  • Adjustment: annual household income, maternal education
Kamper-Jorgensen et al., 200836 (Denmark)

  • 559 ALL (199 c-ALL)

  • Diagnosed 1989–2004

  • Age 0–15 years

  • All cases of childhood leukaemia identified in a cohort of all children in Denmark

 5590 individually matched children selected from population registers Records-based data from three population-based registries: The Nordic Society of Paediatric Haematology and Oncology, the Danish Civil Registration System, and the Childcare database Child-care attendance in children during first 2 years of life (yes/no) ALL: 0.68 (0.48, 0.95) c-ALL: 0.58 (0.36, 0.93)

  • Individual match: date of birth, sex, birth cohort

  • Adjustment: several demographic characteristics was considered but none were major confounders

SES, socioeconomic status; RDD, random digit dialing; UKCCS, United Kingdom Childhood Cancer Study.