Severe maternal morbidity in Canada, 2003 to 2007: surveillance using routine hospitalization data and ICD-10CA codes.
OBJECTIVE
To examine the feasibility of using routine labour and delivery hospitalization data and international classification of diseases (ICD-10CA) codes for carrying out surveillance of severe maternal morbidity in Canada.


METHODS
We identified ICD-10CA diagnosis codes and Canadian Classification of Interventions (CCI) procedure codes associated with severe maternal illness. Severe maternal morbidity rates in Canada (excluding Quebec) for the period 2003 to 2007 were estimated using the Discharge Abstract Database of the Canadian Institute for Health Information. Rates were compared across maternal age, parity, plurality, labour induction, delivery by Caesarean section, and other factors. Case fatality rates and length of hospitalization were also estimated.


RESULTS
Among the 1 336 356 women who delivered between 2003 and 2007, the rate of severe maternal morbidity was 13.8 per 1000 deliveries. The mean length of hospital stay for women with and without a severe illness was 5.4 days vs. 2.5 days, while the frequency of prolonged hospital stay (>or=7 days) was 19.8% vs. 1.8%, respectively (rate ratio 9.3; 95% CI 9.0 to 9.6). Case fatality rates differed significantly between women with and without a severe illness at 2.98 vs. 0.008 per 1000, respectively (rate ratio 392.8; 95% CI 200.3 to 700.4). Rates of severe maternal morbidity were higher among deliveries to older and nulliparous women and to those delivering twins or triplets.


CONCLUSIONS
Disease frequency, case fatality, and length of hospitalization patterns suggest that comprehensive and timely surveillance of severe maternal morbidity in Canada is feasible using the Canadian Institute for Health Information hospitalization data and ICD-10CA/CCI codes.
Department of Obstetrics and Gynaecology, University of British Columbia, Vancouver BC; School of Population and Public Health, University of British Columbia, Vancouver BC.
K S
KS
Joseph
Maternal and Infant Health Section, Public Health Agency of Canada, Ottawa ON.
Shiliang
S
Liu
Maternal and Infant Health Section, Public Health Agency of Canada, Ottawa ON.
Jocelyn
J
Rouleau
Department of Community and Family Health, University of South Florida, Tampa FL.
Russell S
RS
Kirby
Department of Pediatrics, McGill University, Montreal QC; Department of Epidemiology and Biostatistics, McGill University, Montreal QC; Canadian Institutes of Health Research, Ottawa ON.
Michael S
MS
Kramer
Department of Pediatrics, University of Calgary, Calgary AB; Department of Community Health Sciences, University of Calgary, Calgary AB.
Reg
R
Sauve
Department of Obstetrics and Gynecology, University of Montreal, Montreal QC.
William D
WD
Fraser
Department of Obstetrics and Gynaecology, Dalhousie University, Halifax NS.
David C
DC
Young
Department of Obstetrics and Gynaecology, University of British Columbia, Vancouver BC.
Robert M
RM
Liston
D000293:Adolescent; D000328:Adult; D002170:Canada; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007902:Length of Stay / Q000706:statistics & numerical data; D008423:Maternal Age; D010298:Parity; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology*; D011272:Pregnancy, Multiple; D012720:Severity of Illness Index; D055815:Young Adult