Emergency department (ED) visits for non-traumatic dental conditions (NTDC) continue to attract advocacy and policy attention in Canada. (1,2) Generally, ED visits for NTDC are viewed as an inefficient and costly way of dealing with such dental problems, which are most often basic in nature and best treated in office-based ambulatory dental settings. (3-6) In fact, ED visits for NTDC are now viewed as a consequence of poor access to dental care and are used in some jurisdictions as an indicator in this regard. (6)

National-level data in the United States suggest that, over a 10-year period, ED visits for NTDC increased and at a faster rate than for all ED visits combined. (7) Yet, in Canada, most studies on ED visits for NTDC present data for only one or two years; (4,5) only one has presented trend data, but it was limited to homeless adults over a four-year period in one Ontario municipality. (3) Trend data are important, as they give researchers and policy-makers the ability to explore patterns in a given outcome, and allow for hypothesis formulation on potential environmental exposures and their effects on such trends.

Further, though most studies on ED visits for NTDC in Canada quantify the burden, they do not report on the predictors of such visits either at the individual or area-based level. (4,5) What is known has relied on data on self-reported ED visits for NTDC in Canada, and suggests that cost barriers to dental care, oral pain, and bed days due to dental problems are predictors of such visits. (8,9)

As a result of the above, this study aims to assess trends in ED visits for NTDCs in Ontario from 2006 to 2014, and to explore socio-demographic and geographic predictors of such visits.

METHODS

Data aggregated at the region level (14 Local Health Integration Networks, or LHINs) for ED visits in Ontario for NTDCs related to the hard tissues of teeth (described below) were obtained from the Canadian Institute for Health Information's (CIHI) National Ambulatory Care Reporting System (NACRS). Population-based data (as these included everyone from the existing administrative data and not just a representative sample) were available from fiscal year 2006/2007 to 2014/2015. Data included both the number of people who made visits to EDs and the number of visits they made.

Cells with four or fewer observations were suppressed to avoid identification.

Based on the census year 2006 (as long forms were not mandatory in 2011), postal codes of individuals were used to assign dissemination areas (DA), which in turn were linked to neighbourhood characteristics: urban/rural setting, income, and proportion of immigrants. Details are as follows: 1) Neighbourhood urban/rural: Census metropolitan area (CMA) or census agglomeration (CA) of [greater than or equal to] 10 000 residents is considered urban and of <10 000 is considered rural;2) Neighbourhood income quintile: CMAs/CAs are divided into income quintiles ranked 1 to 5 (poorest, poorer, average, richer and richest) according to the percentage of their population below the low-income cut-off, where low-income refers to a total family income in the year preceding the Census that is below that year's Statistics Canada low-income cut-off, which varies according to family size and CMA/CA size; and 3) Neighbourhood immigrant tercile: the DAs are divided into three approximately equal-sized groups based on percentage of immigrants: with the highest, the middle and the lowest tercile corresponding to immigrant proportions of 63%, 37% and 10% respectively. (10)

In NACRS, there are two relevant variables: the presenting complaint list (data element 136) and the ED discharge diagnosis (data element 137). (11) The presenting complaint list includes self-reported reasons and symptoms for seeking medical care, and the ED discharge diagnosis shortlist (CED-DxS) includes diagnoses in common terms, which are mapped to ICD-10-CA codes. (11) We included cases for which the discharge diagnoses (ICD-10-CA code) confirm a non-traumatic dental condition related to the hard tissues of teeth, such as dental caries (K02.9), periapical abscess without sinus (K04.7), and tooth ache (K08.87). Conditions related to soft tissues of the oral cavity, such as ulceration or stomatitis of gum, tongue and/or cheek mucosa, or involving salivary glands, were not included since physicians can also treat these oral conditions. As the purpose of this research is to assess the burden on the health care system due to dental diseases that can solely be resolved by dental professionals, any oral condition which can be handled by other health professionals was excluded. People with mild or moderate intellectual and developmental disabilities (IDDs) (12) are generally at an increased risk of dental disease due to co-morbidities, dietary practices, behavioural challenges, and the potential need for extra attention in oral hygiene maintenance (e.g., tooth brushing); though these individuals can be treated successfully in the general practice setting, ED visits are not necessarily preventable for them, and therefore they were excluded from analysis. (13,14) Given the above, if the discharge summary included ICD codes related to dental trauma, oral soft tissues or developmental disability, those cases were excluded from the analysis.

Descriptive analysis was performed. Data were examined for the whole of Ontario and stratified by LHINs. Both number of people and number of visits made by those people (some people visit multiple times), stratified by sex and age groups (0-5, 6-18, 19-64, and 65+ years), were tabulated for nine consecutive years. Rates were calculated by dividing the number of people visiting the ED in each fiscal year by the projected population based on Statistics Canada estimates for that fiscal year. (15) Kendall's tau, a non-parametric test, was utilized to conduct a time trend analysis of visits over the nine-year time period. (16) We also examined both number of people and number of visits stratified by neighbourhood characteristics; however, rates could not be calculated for income quintiles and immigrant terciles because of neighbourhood migration creating uncertainty in available population denominators.

RESULTS

From 2006 to 2014, on average, 53 618 visits were made each year to EDs in Ontario for NTDCs by approximately 44 848 people. Over the nine-year period of observation, this totals approximately 482 565 visits made by 403 628 people.

In terms of rates, each year approximately 341/100 000 people visited EDs for NTDCs. Stratified by sex, each year approximately 24106 men (413/100000) and 20 742 women (351/100000) visited EDs for NTDCs (Table 1). By age, each year children aged 0-5 years was the age group that visited EDs for NTDCs the most at an average of 718 per 100 000, and people aged 65+ visited the least at 394 per 100 000 (Table 1). Among the 14 LHINs, rates were highest in the North East region, at an average of 882 per 100 000 people per year, and lowest in the Mississauga Halton region, at 148 per 100 000 people per year (Table 2).

Over the nine-year period of observation, there was an approximately 10% increase in overall rate of people visiting EDs for NTDCs (from 359/100 000 in 2006 to 399/100 000 in 2014). As per the Kendal tau correlation test, significant positive trends (figure not presented) in overall rates (r = 0.72, p = 0.0091) and for both men (r = 0.75, p = 0.0064) and women (r = 0.78, p = 0.0049) individually, were observed from 2006 to 2014.

By neighbourhood income quintile, on average, the number of visits made to EDs each year for NTDCs was 2.3 times higher among those living in the lowest neighbourhood income quintile (approximate average 15 856 visits per year) compared to those living in the highest (approximate average 6840 visits per year) (Figure 1). By neighbourhood immigrant tercile, people living in the tercile with the highest immigrant concentration (approximate average 39 759 visits per year) visited approximately nine times more often as those living in neighbourhoods in the tercile with the lowest immigrant concentration (approximate average 4429 visits per year) (Figure 2). By rural/urban stratification, people in rural regions visited EDs for NTDCs almost twice (approximate average 600 people per 100 000 per year) as often as people in urban regions (approximate average 313 people per 100 000 per year) (Figure 3). In terms of trends, the number of visits to EDs for NTDCs consistently increased among all quintiles, terciles and regions, and each trend was statistically significant based on Kendal tau results (correlation and p values are presented in respective figures).

DISCUSSION

We set out to examine trends over time (2006-2014) in ED visits for NTDCs in Ontario, overall and stratified by age, sex, region, and area-level socio-demographic condition (urban/rural, income quintile, and immigrant status). Before this work, only two studies had been completed, which showed the burden on Ontario's health care system due to NTDCs for the years 2003-2006 and 2006-2007. (4,5) Our analysis builds on this research by considering an updated and longer period of observation time.

Our most notable finding is a steady, statistically significant increase in ED visits for NTDCs during this time frame. EDs are an expensive and inefficient option for addressing dental concerns, which would be better addressed in the dental system by dental professionals. (17) However, access to dental care, being inequitable in the Canadian society, can be a possible explanation of these findings. Among OECD countries, Canada fares poorly--including ranking below the United States--in terms of public financing of dental services. (18) In Canada, only approximately 5% of dental care is publicly funded, with jurisdictional variations; provincially, Ontario ranks last, at 1.5%. (19) In this context of limited funding for dental care, our findings speak to a growing burden of health care costs attributed to dental problems.

We also observed large and, in some cases, dramatic discrepancies in ED visits for NTDCs by age and area-level socio-economic indicators. The highest rate of visits was observed in the 0-5 year age group, which is disheartening considering the largely preventable nature of NTDCs and the potential consequences of some NTDCs during childhood for later well-being. (20,21) Though we were not able to compute rates for the area-level stratified analyses, the absolute numbers point to dramatic inequities by neighbourhood income and particularly by immigrant concentrations. Our results corroborate findings of a recent study, where Calvasina et al. showed high unmet dental needs among immigrants in Canada due to low income and lack of dental insurance. (22) We also expect covariation between immigrant and income indicators in our data, but this analysis was not feasible as data obtained were aggregated.

The observation that trends have worsened significantly over time in all groups and are consistently inequitable indicates an important need for both universal and targeted approaches to primary prevention of dental conditions. To enhance equitable access to dental care, policy advocacy is required for publicly funding essential and emergency dental services for all.

Our study has strengths and limitations. The absence of individual-level data on socio-economic circumstances means that misclassification is possible. Due to uncertain denominators, we were unable to compute rates for the stratified analyses with income and immigrant concentrations. Strengths include the ability to access data from the full target population and the high degree of accuracy with which ED visits for NTDCs could be identified.

In terms of future research, similar analyses in other provinces, using consistent methods, would be extremely informative in terms of gauging burden across the country. As a follow-up step, future research should examine: whether rates of ED visits for NTDC vary according to variation in public funding; and changes in rates in response to changes in funding circumstances for dental services. Such analyses would embody a crucial shift in this line of research from the important task of quantifying the extent of the problem, to thinking through potential policy solutions.

doi: 10.17269/CJPH.108.5950

Acknowledgement of Support: Canadian Institute for Health Information for providing data. LM is supported by an Applied Public Health Chair funded by CIHR (Institute of Population & Public Health and Institute of Musculoskeletal Health & Arthritis), the Public Health Agency of Canada, and Alberta Innovates--Health Solutions.

REFERENCES

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(8.) RamrajCC, Quinonez CR. Emergency room visits for dental problems among working poor Canadians. J Public Health Dent 2013; 73(3):210-16. PMID: 23560729. doi: 10.1111/jphd.12015.

(9.) Quinonez C. Self-reported emergency room visits for dental problems. Int J Dent Hyg 2011; 9(1):17-20. PMID: 21226846. doi: 10.1111/j.1601-5037.2009. 00416.x.

(10.) Carriere G, Peters PA, Sanmartin C. Area-based methods to calculate hospitalization rates for the foreign-born population in Canada, 2005/2006. Health Rep 2012; 23(3):43-51. PMID: 23061264.

(11.) Canadian Institution for Health Information. Better Data. Better Decisions. Healthier Canadians. 2016. Available at: https://www.cihi.ca/en/ types-of-care/hospital-care/emergency-and-ambulatory-care/nacrs-metadata (Accessed August 15, 2016).

(12.) US Department of Health and Human Services. National Institutes of Health, Eunice Kennedy Shriver National Institute of Child Health and Development, Intellectual and Developmental Disabilities (IDDs): Condition Information. Available at: https://www.nichd.nih.gov/health/topics/idds/ conditioninfo/Pages/default.aspx (Accessed January 31, 2017).

(13.) Norwood KW Jr., Slayton RL, Council on Children With Disabilities, Section on Oral Health. Oral health care for children with developmental disabilities. Pediatrics 2013; 131(3):614-19. PMID: 23439896. doi: 10.1542/peds.20123650.

(14.) Seirawan H, Schneiderman J, Greene V, Mulligan R. Interdisciplinary approach to oral health for persons with developmental disabilities. Spec Care Dentist 2008; 28(2):43-52. PMID: 18402616. doi: 10.1111/j.1754-4505. 2008.00010.x.

(15.) Statistics Canada. Population, urban and rural, by province and territory (Ontario). Ottawa, ON: Statistics Canada, 2011. Available at: http://www. statcan.gc.ca/tables-tableaux/sum-som/l01/cst01/demo62a-eng.htm (Accessed January 31, 2017).

(16.) Ely JW, Dawson JD, Lemke JH, Rosenberg J. An introduction to time-trend analysis. Infect Control Hosp Epidemiol 1997; 18(4):267-74. doi: 10.2307/ 30141214.

(17.) Allareddy V, Rampa S, Lee MK, Allareddy V, Nalliah RP. Hospital-based emergency department visits involving dental conditions: Profile and predictors of poor outcomes and resource utilization. J Am Dent Assoc 2014; 145(4):331-37. PMID: 24686965. doi: 10.14219/jada.2014.7.

(18.) OECD. StatExtracts Database. Paris: Organisation for Economic Co-operation and Development. Available at: http://stats.oecd.org/ (Accessed October 27, 2016).

(19.) Yalnizyan A, Aslanyan G. Putting Our Money Where Our Mouth Is: The Future of Dental Care in Canada. Ottawa, ON: Canadian Centre for Policy Alternatives, 2011.

(20.) The Impact of Oral Disease. Albany, NY: New York State Department of Health, 2006. Available at: https://www.health.ny.gov/prevention/dental/ impact_oral_health.htm (Accessed October 27, 2016).

(21.) Gift HC, Reisine ST, Larach DC. The social impact of dental problems and visits. Am J Public Health 1992; 82(12):1663-68. doi: 10.2105/AJPH.82.12. 1663.

(22.) Calvasina P, Muntaner C, Quin onez C. Factors associated with unmet dental care needs in Canadian immigrants: An analysis of the longitudinal survey of immigrants to Canada. BMC Oral Health 2014; 14:145. doi: 10.1186/14726831-14- 145.

Received: October 31, 2016

Accepted: March 18, 2017

Sonica Singhal, BDS, MPH, PhD, [1,2] Lindsay McLaren, PhD, [3] Carlos Quinonez, DMD, MSc, PhD [1]

[1.] Dental Public Health, University of Toronto, Toronto, ON

[2.] Health Promotion, Chronic Disease and Injury Prevention Department, Public Health Ontario, Toronto, ON

[3.] Department of Community Health Sciences, University of Calgary, Calgary, AB

Correspondence: Sonica Singhal, PhD, Dental Public Health, University of Toronto, 124 Edward Street, Toronto, ON M5G 1G6, Tel: 647-525-2077, E-mail: sonica. singhal@mail.utoronto.ca

Conflict of Interest: None to declare.

Table 1. Nine-year trends of rate of people per 100 000 visiting EDs
for NTDCs, stratified by sex and age groups

Age groups     2006        2007        2008        2009
(years)
              F     M     F     M     F     M     F     M

0-5          646   742   643   734   653   787   631   796
6-18         214   236   222   251   242   266   245   271
19-64        299   363   319   380   326   386   317   386
65+          167   206   176   224   182   219   173   215
Overall      332   387   340   397   351   414   342   417

Age groups     2010        2011        2012        2013        2014
(years)
              F     M     F     M     F     M     F     M     F     M

0-5          645   757   708   800   660   766   665   793   691   797
6-18         235   265   258   285   250   278   257   289   275   289
19-64        326   395   336   399   336   401   334   396   346   399
65+          174   222   178   218   171   228   171   218   182   216
Overall      345   410   370   425   354   418   357   424   373   425

Table 2. Nine-year trends of rate of people per 100 000 visiting EDs
for NTDCs, stratified by LHINs

Region                 2006   2007   2008   2009   2010   2011

Mississauga Halton     152    137    136    144    147    153
Central                135    139    144    140    149    153
Toronto Central        164    169    173    180    188    199
Central West           165    167    170    172    175    190
Central East           299    310    322    303    313    313
Waterloo Wellington    262    291    277    304    298    316
Hamilton Niagara       336    352    353    327    329    322
  Haldimand Brant
Champlain              327    338    321    321    321    365
South West             461    502    525    513    509    528
Erie St. Clair         580    613    634    615    614    623
North Simcoe Muskoka   480    541    519    500    533    541
South East             503    543    573    597    616    630
North West             707    780    801    872    938    930
North East             733    747    884    903    877    918

Region                 2012   2013   2014

Mississauga Halton     151    149    148
Central                156    161    164
Toronto Central        201    185    187
Central West           198    189    191
Central East           307    306    316
Waterloo Wellington    311    306    324
Hamilton Niagara       339    333    341
  Haldimand Brant
Champlain              334    350    356
South West             524    508    543
Erie St. Clair         585    576    580
North Simcoe Muskoka   549    621    608
South East             620    614    626
North West             931    910    897
North East             939    953    984

Note: LHINs are arranged from the least to the highest rates, based
on 2014 results.

Figure 1. Nine-year trends of number of visits made to EDs for
NTDCs, stratified by neighbourhood income quintile. * Kendal tau
correlations: Quintile 1 (poorest): r = 0.89, p = 0.0012;Quintile 2
(poorer): r = 0.94, p = 0.0006;Quintile 3 (middle):
r = 0.83, p = 0.0025;Quintile 4 (richer): r = 0.89, p =
0.0012;Quintile 5 (richest): r = 0.89, p = 0.0012.

       Quintile 1   Quintile 2   Quintile 3   Quintile 4   Quintile 5

2006   14372        10373        8602         7389         6062
2007   15126        10872        8414         7880         6274
2008   15576        11401        9702         8350         6709
2009   15557        11226        9512         8349         6710
2010   15,792       11,450       9,952        8,809        6,845
2011   16,323       12,169       10,479       9,221        7,135
2012   16,196       12,208       10,452       9,178        7,234
2013   16,761       12,324       10,471       9,482        7,055
2014   16,998       12,494       10,780       9,704        7,538

Note: Table made from line graph.

Figure 2. Nine-year trends of number of visits made to EDs for
NTDCs, stratified by immigrant tercile. * Kendal tau
correlations:
Tercile 1: r = 0.89, p = 0.0012;Tercile 2: r = 0.83, p = 0.0025;and
Tercile 3: r = 0.83, p = 0.0025.

       Tercile 1   Tercile 2   Tercile 3

2006   35240       6875        3922
2007   37535       7220        4051
2008   39190       7546        4130
2009   38904       7378        4245
2010   39660       7750        4103
2011   41396       8188        4536
2012   40934       8331        4895
2013   41926       8071        5013
2014   43043       8435        4962

Note: table made from line graph.

Figure 3. Nine-year trends of rate of visits per 100 000 people
made to EDs for NTDCs, stratified by region: rural/urban. *
Kendal tau correlations: rural: r = 0.89, p = 0.012;urban:
r = 0.89, p = 0.025.

       Rural   Urban

2006   536     296
2007   555     309
2008   606     311
2009   596     308
2010   603     313
2011   623     322
2012   615     320
2013   620     318
2014   642     323

Note: Table made from line graph.