Birth Prevalence of Cleft Lip and Cleft Palate in British Columbia : Between 1985 and 2004

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Soo-Hong Uh, Carlos Caraveo, Leslie T. Foster, R. Brian Lowry

Introduction:

To investigate the trends and geographical variations in birth prevalence of orofacial cleft malformations between 1985 and 2004, we extracted data specific to defect type, gender and isolated defects from the province-wide population-based congenital anomalies surveillance program, British Columbia (B.C.) Health Status Registry. To obtain comparative information about both infants and mothers, we merged a total 1,910 cases of Cleft Defects to the B.C. vital statistics birth registrations to create a birth cohort totaling 871,012 total births over this same time period.

Over the last twenty-year study period, the birth prevalence proportions of Cleft Lip with or without Cleft Palate and of isolated Cleft Lip and isolated Cleft Palate fluctuated with an annual decrease in rates for all cases combined. In comparison to Lowry et al’s [1] findings, it appears as though the prevalence rates per 1,000 total births for Cleft Lip with and without Cleft Palate are higher during the years 1985 to 2004 than during the previous, 1952 to1986 study period. Although the prevalence rates of orofacial defects were lower during the period of 1952 to 1986, our follow up data suggests that these higher rates (1985-2004) have been steadily decreasing over the most recent twenty years.

Methods:

The British Columbia Health Status Registry (hereafter called as the BCHSR) collects and registers any residents with congenital anomalies and genetic conditions in the province under the British Columbia Health Act. These data are published annually and are available on the B.C. Vital Statistics Agency (BCVSA) website (http://www.vs.gov.bc.ca/stats/hsr/index.html). The BCHSR, operated by the BCVSA, maintains data including the malformation categories; Cleft Palate (CP), Cleft Lip (CL), and Cleft Lip with Cleft Palate (CL+CP). Cases with the defects of CP/CL/CL+CP were extracted from BCHSR database using the International Classification of Disease 9 th Revision (ICD-9) and ICD-10 codes over the 20 year period, 1985-2004.

In order to capture the birth particulars such as mother’s age, gestational age, birth weight, and type of birth such as singleton or multiple, and information on the mother’s country of birth, for each individual, the file was matched to the provincial Vital Statistics birth registrations. This study has reviewed the data from the most recent twenty years (1985-2004). The study also investigated the differences of birth prevalence rates between Status Indian (SI) and Non-Status Indian (Non-SI). The SI status indicator ([4] for Status Indian definition) was obtained from a BCVSA’s previous study for the years 1995-2002 only. Data for later years are awaiting the outcome of negotiations of data access on the Status Verification File from Health Canada and Indian and Northern Affairs Canada.

The birth prevalence rates for the malformation categories, CP, CL, CL+CP, and the combined CL with and without CP (CL+/-CP) were calculated based on 1,000 total births (live births and stillbirths) in British Columbia. With the recent data access arrangements, the information of medically induced pregnancies due to congenital anomalies will be included in the future studies.

Results:

In British Columbia, over the twenty-year study period from 1985 to 2004, there were a total of 768 babies born with the defects of Cleft Palate (CP), and a further 1,142 born with Cleft Lip (CL), or Cleft Lip with Cleft Palate (CL+CP). The total number of cleft defects was 1,910. The birth prevalence rate of 1.64 per 1,000 total births (71 cases) in 1985 declined by more than 30% to 1.11 (45 cases) in 2004 for the defects of Cleft Lip with or without Cleft Palate (CL+/-CP). While there were fluctuations from year to year, overall there has been a fairly steady decrease in both types of defects: CP and CL+/-CP. The highest rates occurred in 1990 and 1991 with rates of 1.84 (84 cases) and 1.32 (60 cases) for the defects of CL+/-CP and CP, respectively while the prevalence was shown to be the same in 2003 (Table 1 and Figure 1).

Table 1.
Number and Prevalence Rates of Cleft Defects By Diagnosis Type British Columbia, 1985-2004

Note: CP: Cleft Palate, CL+/-CP: Cleft Lip with and without Cleft Palate Rate: per 1,000 Total Births, and Based on B.C. Residents only.

Table 2 shows that there was a much higher prevalence rate for males (1.58/1,000 total births or 708 cases) than for females (0.96 or 406 cases) in Cleft Lip with and without Cleft Palate (CL+/-CP) over the twenty-year period. While the average female prevalence (0.91 or 385 cases) of cleft palate (CP) shows a higher rate than for males (0.81 or 362 cases) over the same twenty-year period, in six of those twenty years, the male rate was higher than the female rate. Over the total period of study, the highest rate for males born with CP occurred in 1991 (1.24/1,000 total births) and for females in 1990 (1.30/1,000). Overall, there have been declining trends in the birth prevalence rates for both genders, with slightly more decline for female CP and with a more declining trend for male CL+/-CP (Figure 2(a) and Figure 2(b)).

Table 2.Number and Prevalence Rates of Cleft Defects By Gender
British Columbia, 1985-2004

	CP				CL				CL+CP				CL+/-CP
	Male		Female		Male		Female		Male		Female		Male		Female
Year	No. of Cases	Rate	No. of Cases	Rate	No. of Cases	Rate	No. of Cases	Rate	No. of Cases	Rate	No. of Cases	Rate	No. of Cases	Rate	No. of Cases	Rate
1985	20	0.91	20	0.94	10	0.45	6	0.28	28	1.27	24	1.13	38	1.72	30	1.41
1986	19	0.88	22	1.07	13	0.60	5	0.24	31	1.44	10	0.49	44	2.05	15	0.73
1987	16	0.74	15	0.74	7	0.33	9	0.44	20	0.93	12	0.59	27	1.26	21	1.03
1988	24	1.09	26	1.23	8	0.36	3	0.14	23	1.04	20	0.95	31	1.41	23	1.09
1989	26	1.16	22	1.03	12	0.53	4	0.19	26	1.16	14	0.65	38	1.69	18	0.84
1990	19	0.81	29	1.30	15	0.64	4	0.18	43	1.84	18	0.81	58	2.49	22	0.99
1991	29	1.24	28	1.26	20	0.85	6	0.27	28	1.20	12	0.54	48	2.05	18	0.81
1992	22	0.93	25	1.11	15	0.63	4	0.18	34	1.43	11	0.49	49	2.07	15	0.66
1993	9	0.38	20	0.89	8	0.34	6	0.27	38	1.60	17	0.76	46	1.94	23	1.02
1994	17	0.70	17	0.75	13	0.53	5	0.22	24	0.99	27	1.19	37	1.52	32	1.40
1995	22	0.91	24	1.06	10	0.41	3	0.13	24	0.99	13	0.57	34	1.40	16	0.70
1996	22	0.92	26	1.16	12	0.50	10	0.45	29	1.22	12	0.54	41	1.72	22	0.98
1997	17	0.74	11	0.50	5	0.22	11	0.50	23	1.01	17	0.78	28	1.23	28	1.28
1998	14	0.64	23	1.09	5	0.23	14	0.66	29	1.32	11	0.52	34	1.54	25	1.18
1999	16	0.74	14	0.69	10	0.46	4	0.20	22	1.01	14	0.69	32	1.47	18	0.88
2000	23	1.10	14	0.71	10	0.48	10	0.50	21	1.00	14	0.71	31	1.48	24	1.21
2001	16	0.77	18	0.91	5	0.24	6	0.30	14	0.67	14	0.71	19	0.91	20	1.01
2002	11	0.53	18	0.93	10	0.48	4	0.21	21	1.01	9	0.46	31	1.49	13	0.67
2003	13	0.63	8	0.40	4	0.19	3	0.15	7	0.34	7	0.35	11	0.53	10	0.51
2004	7	0.34	5	0.25	12	0.58	6	0.30	19	0.91	7	0.35	31	1.49	13	0.66
Total	362	0.81	385	0.91	204	0.46	123	0.29	504	1.13	283	0.67	708	1.58	406	0.96

Note: CP: Cleft Palate, CL+/-CP: Cleft Lip with and without Cleft Palate
Rate: per 1,000 Total Births, Gender Unknowns – excluded, and Based on B.C. Residents only.

While there have been fluctuations in the last two decades for the defects of isolated and non-isolated CP and CL+/-CP, overall there has been a downward trend. However, the birth prevalence rate was generally higher for non-isolated cleft defects in British Columbia (Table 3). Non-isolated refers to any additional congenital anomaly including defined syndromes (Trisomy 13, Smith Lemli Opitz, etc.). At an average prevalence rate of 0.77/1,000 total births over the twenty-year period, the non-isolated rate was more than 50% higher than the average isolated rate of 0.51/1,000 for CL+/-CP. The highest rates of non-isolated CL+/-CP occurred in 1998 (1.04 per 1,000 total births) while the highest rate for isolated CL+/-CP was 0.92 in 1990. Over the 20-year study period, there was a greater decline in the trend of the non-isolated CP versus isolated CP (Figure 3(a)) while isolated CL+/-CP shows a steady decline from 1990 to 2003 (Figure 3(b)).

Table 3.Number and Prevalence Rates of Cleft Defects By Isolated Type
British Columbia, 1985-2004

	CP				CL				CL+CP				CL+/-CP
	Isolated		Non- Isolated		Isolated		Non- Isolated		Isolated		Non- Isolated		Isolated		Non- Isolated
Year	No. of Cases	Rate	No. of Cases	Rate	No. of Cases	Rate	No. of Cases	Rate	No. of Cases	Rate	No. of Cases	Rate	No. of Cases	Rate	No. of Cases	Rate
1985	18	0.42	22	0.51	7	0.16	9	0.21	22	0.51	30	0.69	29	0.67	39	0.90
1986	17	0.40	24	0.57	12	0.29	6	0.14	11	0.26	30	0.71	23	0.55	36	0.86
1987	13	0.31	18	0.43	9	0.21	7	0.17	12	0.29	20	0.48	21	0.50	27	0.64
1988	13	0.30	37	0.86	7	0.16	4	0.09	18	0.42	26	0.60	25	0.58	30	0.70
1989	19	0.43	29	0.66	12	0.27	4	0.09	17	0.39	23	0.52	29	0.66	27	0.62
1990	19	0.42	29	0.64	11	0.24	8	0.18	31	0.68	30	0.66	42	0.92	38	0.83
1991	21	0.46	36	0.79	16	0.35	10	0.22	19	0.42	21	0.46	35	0.77	31	0.68
1992	20	0.43	27	0.58	12	0.26	7	0.15	11	0.24	34	0.73	23	0.50	41	0.89
1993	15	0.32	15	0.32	6	0.13	8	0.17	22	0.48	33	0.71	28	0.61	41	0.89
1994	14	0.30	21	0.45	12	0.25	6	0.13	21	0.45	30	0.64	33	0.70	36	0.76
1995	14	0.30	32	0.68	12	0.26	1	0.02	10	0.21	27	0.57	22	0.47	28	0.60
1996	24	0.52	25	0.54	12	0.26	11	0.24	12	0.26	29	0.63	24	0.52	40	0.87
1997	11	0.25	17	0.38	9	0.20	7	0.16	14	0.31	29	0.65	23	0.51	36	0.81
1998	22	0.51	15	0.35	6	0.14	13	0.30	8	0.19	32	0.74	14	0.32	45	1.04
1999	8	0.19	22	0.52	3	0.07	11	0.26	9	0.21	28	0.67	12	0.29	39	0.93
2000	11	0.27	27	0.66	7	0.17	13	0.32	9	0.22	26	0.64	16	0.39	39	0.96
2001	19	0.47	16	0.39	1	0.02	10	0.25	9	0.22	19	0.47	10	0.25	29	0.71
2002	16	0.40	13	0.32	4	0.10	10	0.25	8	0.20	22	0.55	12	0.30	32	0.80
2003	10	0.25	11	0.27	1	0.02	6	0.15	3	0.07	11	0.27	4	0.10	17	0.42
2004	3	0.07	9	0.22	9	0.22	9	0.22	14	0.34	13	0.32	23	0.57	22	0.54
Total	307	0.35	445	0.51	168	0.19	160	0.18	280	0.32	513	0.59	448	0.51	673	0.77

Note: CP: Cleft Palate, CL+/-CP: Cleft Lip with and without Cleft Palate
Rate: per 1,000 Total Births, Gender Unknowns – excluded, and Based on B.C. Residents only.

Table 4(a) and Table 4(b) provide selected data for the birth prevalence of Cleft Palate (CP) and Cleft Lip with or without Cleft Palate (CL+/-CP) by mother’s age for the period 1995 to 2004. The prevalence rates were higher for CP and were markedly higher for CL+/-CP in children born to mothers less than 20 years of age than in children born to mothers aged 20-34 and 35+ years age groups. Over the ten-year study period the prevalence rates of CP and CL+/-CP in children born to mothers aged 20-34 and 35+ years decreased annually with fluctuations. In contrast, the prevalence rates of CP and CL+/-CP in children born to mothers less than age 20 fell over at the beginning or the first part of the period and then increased in the second part, so that rates were actually higher than for mothers over age 20 years (Figure 4(a) and 4(b)).

The prevalence rates of CP and CL+/-CP in children born before 37 weeks of gestation were much higher on average (1.62/1,000 vs. 0.57/1,000 and 1.81/1,000 vs. 0.84/1,000 total births respectively), and higher in almost all 10 years except 1995, than in children born 37 weeks and over. The average prevalence rate for CP children born with low birth weight (< 2,500 g), at 2.00/1,000 total births is nearly three times higher than the rate (0.61/1,000) for children born with birth weights 2,500 g and over while the rate for CL+/-CP of 2.13/1,000 for LBW children is more than double of the rate of 0.90/1,000 for children born with 2,500 g and over (Table 4(a) and Table 4(b)). In 2000, the rate for low birth weight babies was a remarkable 4.94/1,000 total births for CL+/-CP.

The Figures 4(c) to 4(e) showed downward trends for both type of defects (CP and CL+/-CP) except the prevalence rates increased for CL+/-CP children born with LBW (Figure 4(f).

Between the years of 1995 and 2004, the total number of singleton birth cleft defects (CP and CL+/-CP) dramatically outweighed the total number of multiple birth cleft defects, as would be expected given the much lower number of multiple births in general (Table 4(a) and Table 4(b)). The average prevalence rate for CP multiple births (0.90/1,000), however, was more than 30% higher than the rate for CP singleton births (0.68 per 1,000 total births) while the rate of CL+/-CP 1.08/1,000 was slightly higher (over 10%) for multiple births than the rate of singleton births 0.98. With fluctuations the rates decreased over the 10-year study period (Figure 4(g) and Figure (h)) except the years 2000 and 2001 for CL+/-CP.

Table 4(a) and Table 4(b) also show that the average birth prevalence rates of both CP and CL+/-CP (1.07/1,000 and 1.60/1,000 respectively) for Status Indians were about 30% higher than that of Non-Status Indians (0.84/1,000 and 1.21/1,000 total births for CP and CL+/-CP respectively) over the years 1995-2002. In three of the eight years for CP and in two out of eight years for CL+/-CP, however, the Status Indian prevalence rate was lower than the Non-Status Indian rate. Given the relatively small numbers overall for Status Indian birth cleft defect, caution should be practiced before coming to any general conclusions. The trends of rate for CP and CL+/-CP show dramatically decreasing for Status Indian over the time period of 1995 to 2002 (Figure 4(i) and Figure 4(j)).

Table 4(a) Number and Rates by Birth Particulars Cleft Palate British Columbia, 1995-2004

Table 4(b) Cleft Lip with or without Cleft Palate Number and Rates by Birth Particulars British Columbia, 1995-2004

Figure 5 provides a clear comparison among B.C. mothers based on their country of birth, At a birth prevalence rate of 2.88/1,000 total births of the combined cleft defects, the children whose mothers were born in Germany have by far the highest rate, followed by those born in the Philippines (1.91/1,000) followed by Canadian born mothers (1.88/1,000). By contrast, B.C. mothers born in India (1.18/1,000) and China (1.36/1,000) had substantially lower rates.

Figure 5.
Prevalence Rates of Cleft Defects By Mother's Country of Birth, British Columbia, 1985-2004

Geographic perspectives on prevalence rates throughout the province of British Columbia are provided in Figure 6, based on 16 Health Services Delivery Areas (HSDA). In addition, Figure 7 (Map) provides a more detailed map based on 89 Local Health Areas (LHA) in the province. The three highest prevalence rates occurred in HSDA Thompson Cariboo Shuswap (2.64/1,000), Northern Interior (2.49/1,000), and Central Vancouver Island (2.62/1,000). The three lowest HSDA prevalence rates occurred in North Shore/Coast Garibaldi (1.71/1,000), Kootenay Boundary and East Kootenay (both 1.90/1,000). Much more work is required to understand these variations. For example they may be related to specific clusters only or to specific characteristics of the population such as place of birth of mother or Status Indian ethnicity [4].

Figure 6.
Cleft Defects Rates per 1,000 Total Births by HSDA. British Columbia 1989-2004

Note: Cases with unknown HSDA were excluded

Figure 7 (Map)

Figure 7 (Map) shows a substantial geographical variation within the province based on Local Health Areas. Rates vary from a high of 8.46/1,000 for Central Coast (LHA 83) to no cases at all for seven LHAs. The LHA 15, Penticton (4.11/1,000) has a statistically significant high rate while five LHAs, Vancouver Westside (1.45/1,000), Abbotsford (1.44/1,000), Vancouver City-Centre (1.34/1,000), West Vancouver/Bowen Island (1.14/1,000), Howe Sound (0.99/1,000), have statistically significant low prevalence rates for the period 1989 to 2004. Considerably more analysis is required to get a better understanding of these geographical variations.

Summary and Discussion:

Overall, while there have been fluctuations in prevalence rates, the trends clearly demonstrate reductions over the twenty-year time period of 1985 to 2004 in not only Cleft Palate (CP), but also for Cleft Lip with and without Cleft Palate (CL+/-CP), in British Columbia. In general, the prevalence rate (1.31/1,000) for CL+/-CP is much higher, nearly 50%, than the rate of CP (0.88/1,000 total births). The birth prevalence rate of CL+/-CP for males, at 1.58 per 1,000 total births on average is much higher than the female rate of 0.96/1,000 by more than 60%. In contrast, the prevalence rate of CP has a slightly higher rate for females (0.91/1,000) than for males (0.81/1,000). Since 1985, there have been higher rates for males than for females consistently, except in 1997, and 2001. There have been significant decreases in the last two decades for CL+/- CP isolated and for CP non-isolated cleft defects, while the average rates of non-isolated CP and CL+/-CP (0.77/1,000 and 0.51/1,000 respectively) were nearly 50% higher than the rates of isolated conditions (0.51/1,000 and 0.36/1,000 total births) over the study period of 1985 to 2004.

In British Columbia, there show markedly higher prevalence rates of CP and CL+/-CP in children born to mother’s less than 20 years of age than in children born to mothers aged 20-34 and 35+ years of age groups. Also the study shows much higher rates of CP and CL+/-CP to children with preterm (less than 37 weeks of gestation) or with low birth weight (less than 2,500 grams). For CP and CL+/-CP, the rates show much higher for multiples than for singleton births. In comparison of birth prevalence of CP and CL+/- CP for Status Indian versus other population groups in British Columbia, there show about 30% higher rates for Status Indians than for non-Status Indians over the periods of 1995 to 2002, but caution should be practiced before coming to any general conclusions. Geographically, there are substantial variations in prevalence rates of orofacial defects throughout the Province of British Columbia.

Caution is required in interpreting these results for several reasons. First, with respect to the downward trends described in this paper, part may be related to the possibility of changing ascertainment of conditions over the time period. This could be related to changing policies, administration or personnel. Further, more statistical analysis is required because it may be possible that for the first six years or so (1985 to 1990/1) of the 20-year study period, the trend may actually be increasing, before starting its downward cycle. Secondly, with respect to differences between Status Indians and the rest of the population much more work is required because not all aboriginal peoples who could claim their Indian Status have done so. Further, the numbers for Status Indians are relatively small in an absolute sense and only eight years of data are available. Third, with respect to the geographic variations in prevalence rates throughout the province at the LHA, some LHAs have small populations and this analysis is at a very early stage so results should interpreted accordingly.

Acknowledgements:

The authors would like to thank Chanelle Edwards at Knowledge Management and Technology, BC Ministry of Health, and Brian McKee, consultant for their technical assistance and also staffs at the BC Health Status Registry, BC Vital Statistics Agency for their supports.

References:

1. Lowry RB, Thunem NY , Uh SH: Birth prevalence of cleft lip and palate in British Columbia between 1952 and 1986: stability of rates, CMAJ: 1989;140: 1167-1170.
2. Lowry RB, Trimble BK: Incidence Rates for Cleft Lip and Palate in British Columbia 1952-71 for North American Indian, Japanese, Chinese and Total Populations: Secular Trends over Twenty Years, Teratology 1977; 16:277-284
3. Lowry RB, Renwick DHG: Incidence of Cleft Lip and Palate in British Columbia Indians, J. Med. Genet 1969; 6:67-69.
4. BC Vital Statistics Agency: Regional Analysis of Health Statistics for Status Indians in British Columbia, 1992-2002; April, 2004.
5. BC Vital Statistics Agency: Selected Vital Statistics and Health Status Indicators; Annual Report, 2003; in 2004.
6. BC Vital Statistics Agency: BC Health Status Registry Report 2005: Congenital Anomalies, Genetic Defects, Selected Handicapping Conditions, Birth Data to 2002; in 2005

Affiliations of Authors

1. Soo-Hong Uh, Consultant, Knowledge Management and Technology, B.C. Ministry of Health
2. Carlos Caraveo, Knowledge Management and Technology, B.C. Ministry of Health
3. Leslie T. Foster, School of Child and Youth Care, University of Victoria, British Columbia
4. R. Brian Lowry, Dept. of Medical Genetics, Alberta Children's Hospital, Calgary & Alberta Congenital Anomalies Surveillance System, Alberta Health & Wellness and Section of Medical Genetics, Dept. of Laboratory Medicine, Victoria General Hospital , Victoria , BC . & BC Health Status Registry.

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