Use of acute care hospital services by immigrant seniors in Ontario: A linkage study

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by Edward Ng, Claudia Sanmartin, Jack Tu and Doug Manuel

The percentage of people aged 65 or older in the Canadian population rose from 8% in 1960 to 15% in 2011; by 2036, the figure is expected to be at least 23%.^Note1,Note2 Population aging affects the demand for and cost of health care services,^Note 3-5 given that seniors account for about 45% of provincial/territorial government health care dollars.^Note 6 Hospitals represented an estimated 29% of health care expenditures in 2012. Seniors are not only the largest user group, but per capita spending on hospital visits are consistently higher among seniors.^{Note 6,Note 7}

According to the 2006 Census, 30% of seniors in Canada and 43% of seniors in Ontario are immigrants.^Note8,Note9 The majority of them arrived decades ago and aged in Canada.^Note 8 However, a small percentage (less than 5%) of recent immigrants were seniors, and thereby contributed directly to the growth of the senior population.^Note 10 Furthermore, the shift in immigrant origins away from Europe has made the senior population more diverse,^{Note 11,Note13} a factor that can influence the demand for hospital care.

Information about immigrant seniors’ use of hospital services is limited, largely because hospital administrative records do not include immigration status. This limitation can be overcome if discharge records are linked to databases that contain immigrant-related information. For instance, a pilot study that linked Citizenship and Immigration Canada (CIC) landing records to health services data in British Columbia and Manitoba found that immigrant seniors generally used fewer hospital services than did non-immigrant seniors, although hospitalization rates rose with duration of residence.^Note 14 Other studies linked landing records to physician claims and to mortality data to examine health service use and health outcomes among immigrants in British Columbia, Ontario and Quebec,^Note 15-17 but did not target seniors.

The present analysis compares hospitalization rates and length of stay of immigrant and Canadian-born seniors in Ontario using linked 2006 Census-Discharge Abstract Database information. This linkage makes it possible to add socio-demographic data and immigrant-related characteristics to hospital administrative records.

Data and methods

Data

In Ontario, about 2.4 million household residents responded to the 2006 Census long form, which collected information on immigrant status (place of birth and period of arrival) and on socio-economic characteristics such as living arrangements, education and income. The Discharge Abstract Database (DAD) (Ontario file) contains information on inpatient hospitalizations (about 0.9 million a year) in acute care facilities, which is provided to Statistics Canada by the Canadian Institute for Health Information.^Note 18  Approximately 2.1 million census long-form respondents were linked to the DAD for the years 2000 to 2010, based on name, date of birth and other demographic information, using the Ontario Registered Person Data Base provided by the Ontario Ministry of Health and Long-Term Care. The linkage was approved by Statistics Canada’s Policy Committee. Details about the linkage are available elsewhere.^Note 19

Study sample

This study is based on 279,175 Ontario residents aged 65 or older who lived in private households: 116,410 immigrants and 162,765 Canadian-born. The 2006 Census defined immigrants as people who are, or have been, landed immigrants in Canada. A landed immigrant is not a Canadian citizen by birth, but has been granted the right to live in Canada permanently.^Note 8 This analysis excludes non-permanent residents and refugee claimants (n = 815).

A retrospective cohort approach was used to examine hospitalization during the two years before the 2006 Census (May 17, 2004 through May 16 2006). This approach minimizes potential bias due to losses to follow-up (for example, emigration and death). To ensure that respondents were “eligible” for hospitalization during the two-year study period, immigrant seniors who arrived between 2004 and 2006 were excluded (n = 395). Immigrants were classified by selected world region of origin: Europe, South Asia (Bangladesh, Bhutan, India, Nepal, Pakistan, Republic of Maldives, Sri Lanka), and East Asia (Hong Kong, Japan, Macao, Mongolia, North Korea, People’s Republic of China, Taiwan, Singapore, South Korea). Immigrants were also classified by period of arrival:  long-term (before 1984), medium-term (1984 through 1993) or recent (1994 through 2003).

Study variables

Hospital use (hospitalization) is defined as inpatient hospital acute service use, excluding alternative levels of care. Two measures of hospital use were analysed: access―at least one acute-care hospitalization during the study period, and intensity―total acute-care hospital days for admissions during the study period. The measures were calculated for all-cause hospitalizations and two leading causes among seniors:  circulatory diseases (most responsible diagnosis - ICD10 codes I00 to I99, such as hypertensive/ischemic/pulmonary heart and cerebrovascular diseases, and digestive diseases (most responsible diagnosis - ICD10 codes K00 to K93, such as diseases of liver, oesophagus, stomach and duodenum, peritoneum).

The census covariates used in this study were age (65 to 74 or 75 or older), sex, knowledge of official languages (yes or no), secondary school graduation (yes or no), low income status (yes, no, or not applicable), and residence in a Census Metropolitan Area (CMA) (Toronto, other CMAs, or rest of Ontario). Living arrangements were classified hierarchically―living with children, with spouse, with others, or alone. The Canadian-born population was the reference group.

Methods

Descriptive statistics were used to examine the characteristics of the study cohort. The prevalence of hospitalization in the two years before the 2006 Census and the cumulated average number of days in hospital for all admissions during that period were calculated by the selected characteristics. Chi-square and the Wilcoxon-Mann-Whitney non-parametric test were used to test for differences between subgroups.

Multivariate statistical analysis was employed to disentangle relationships between immigrant-related characteristics and hospitalization, controlling for age, sex, and the census covariates. With a double-hurdle (two-step) model,^Note 20 differences  in the likelihood of hospital admission and in the length of time in hospital were investigated. First, logistic regression was used to estimate the odds of at least one admission (yes/no) during the study period (SAS v9.2). Second, zero-truncated negative binomial regression was used to estimate differences in cumulated length of hospital stay among those who were hospitalized (STATAv11). The latter method was chosen because of the skewed nature of length-of-stay data, and because the variance of hospital use data often exceeds the mean.^{Note 20, Note 21} In zero-truncated negative binomial regression, an incidence rate ratio (IRR) coefficient of less (more) than 1 is interpreted as a decrease (increase) in the expected number of hospital days by a factor of the IRR, holding all other variables constant. For both steps, two sets of regression models were produced: age-/sex-adjusted and fully adjusted.

Results

Descriptive analysis

Immigrants made up 41% of the study cohort of Ontario seniors (n = 279,175) (Table 1). Two-thirds (68%) of these immigrant seniors were from Europe; 8% were from East Asia, and 6%, from South Asia (data not shown). The majority of immigrant seniors (83%) had arrived in Canada before 1984 (data not shown).

Immigrant and Canadian-born seniors were similar in terms of age, sex and level of education. However, they differed in knowledge of official languages, living arrangements, income, and geographic location (Table 1).

Immigrant seniors’ characteristics varied by world region of origin. Those from Europe tended to be older than those from East Asia and South Asia, and more likely to have arrived before 1984. European-born seniors were also more likely than those from East and South Asia to live alone and have knowledge of official languages, but less likely to live in Toronto. Seniors from East Asia were more likely than those from other world regions to be in a low-income category.

An estimated 18% of immigrant seniors in Ontario had been hospitalized at least once in the two years before the 2006 Census; this compared with 22% of Canadian-born seniors (Table 2).  The percentages hospitalized varied from 10% of those from East Asia to 20% of those from Europe. Immigrant seniors who had arrived most recently (1994 through 2003) were less likely than those who had arrived in earlier periods to have been hospitalized.

About 5% of immigrant seniors and 6% of Canadian-born seniors had at least one circulatory disease hospital admission, and around 3% of both groups were hospitalized for digestive diseases.

The cumulative average number of days for all-cause hospitalizations during the two years before the 2006 Census was significantly lower for immigrant than Canadian-born seniors―9.9 versus 10.3 days. The averages for circulatory diseases did not differ significantly (9.4 versus 9.2 days), but for digestive diseases, the average for immigrants was significantly lower (6.7 versus 7.1 days).

Hospitalization (logistic regression)

The age-/sex-adjusted odds of being hospitalized at least once for any cause during the study period were lower among immigrant seniors than among Canadian-born seniors (OR = 0.81) (Table 3). Results varied by period of immigration, with lower odds among recent immigrants. Even when education, income, living arrangements, knowledge of official languages and CMA residence were taken into account, the odds of hospitalization remained significantly lower among immigrants.

Compared with Canadian-born seniors, those from East Asia (OR = 0.40) or South Asia (OR = 0.75) had lower odds of all-cause hospitalization. The odds for European seniors were close to, but still significantly below those for the Canadian-born.  A duration effect was apparent, with lower odds of hospitalization among recent arrivals. Full adjustment reduced the differences, but did not remove the statistical significance, except among medium-term European immigrants and long-term South Asian immigrants.

Overall, immigrant seniors from Europe or East Asia were less likely than Canadian-born seniors to be hospitalized for circulatory and digestive diseases (Table 3). For South Asians, this was true for digestive diseases, but not for circulatory diseases, as their odds of hospitalization (overall, as well as medium- and long-term) did not differ significantly from the odds for Canadian-born seniors.  As well,  medium-term European immigrant seniors’ odds of hospitalization for circulatory and digestive diseases were the same as those of Canadian-born seniors.

Full adjustment changed the results slightly. For example, among recent European and South Asian immigrants, the fully adjusted odds of hospitalization no longer differed significantly from the odds for Canadian-born seniors, especially for circulatory diseases.

Hospital days (truncated negative binomial regression)

Immigrant seniors who were hospitalized (all causes) spent significantly less time in hospital than did Canadian-born seniors (IRR = 0.94), a reflection of the situation among long-term immigrants (Table 4). Full adjustment yielded significantly less time in hospital among recent immigrants as well, but did not change the overall finding that immigrant seniors’ hospital stays tended to be shorter than those of Canadian-born seniors.

Immigrant seniors from Europe and East Asia spent significantly less time in hospital than did Canadian-born seniors. Results varied slightly by period of arrival, but in no case did immigrant seniors’ hospital days significantly exceed those of Canadian-born seniors.

Time in hospital attributable to circulatory diseases did not differ between Canadian-born and immigrant seniors, except those from East Asia whose hospital stays were significantly shorter after full adjustment (IRR = 0.77).

Among seniors hospitalized for digestive diseases, medium-term (1984 to 1993) South Asian immigrants spent significantly more time in hospital than did than the Canadian-born.  By contrast, medium-term immigrants from Europe spent significantly less time in hospital for digestive diseases than did Canadian-born seniors.

Discussion

This study is unique in its use of linked hospital and census data to compare hospitalization rates and length of stay among Ontario seniors by immigrant status. Over a two-year period, immigrant seniors had lower odds of all-cause and selected cause hospitalization than did Canadian-born seniors.  Adjusting the results for socio-economic covariates available in the census reduced the differences, but with minor exceptions, did not change the overall results.

The findings of previous Canadian studies of immigrants’ use of health care services have varied.  Analyses of self-reported data have shown similar or lower utilization rates for immigrants, compared with the Canadian-born.^{Note 22, Note 23}  Recent studies using administrative data^Note 24-26 found both lower and higher health care service utilization for immigrants, depending on the service and/or immigrant category. A study that linked health care data to immigration landing data reported fewer visits to specialists among immigrants in British Columbia and Ontario.^Note 16 An analysis of hospitalization data and aggregated census data for Toronto showed higher hospitalization rates among people in neighborhoods with relatively large percentages of recent immigrants, but concluded that the results were heavily influenced by the socio-economic characteristics of the neighborhoods.^Note 25 Most of these  studies presented overall comparisons by immigrant status, and did not focus on seniors.

Lower use of hospital services may reflect unmet needs for care, or alternatively, differences in health status.  Although the presence of unmet medical needs among immigrants has been suggested,^Note 27  lower utilization may be due to differences in cultural beliefs and behaviours^Note 28 and/or lower health literacy.^Note 29

Survey-based research found that the health status of recent senior immigrants was similar to or less favourable than that of the Canadian-born population,^{Note 30, Note 31} and that immigrant seniors were more likely to experience health decline but less likely to be hospitalized. These results suggest service underutilization or unmet health needs.^Note 27 Therefore, it might be expected that immigrant seniors who do access care may be sicker and spend more days in hospital than their Canadian-born counterparts. However, the present analysis study generally shows less time in hospital among immigrants. Immigrants’ period of arrival and by cause, immigrant seniors’ hospital stays tended to be shorter or equal to those of the Canadian-born, but not higher, except for digestive diseases among South Asians. Further research is necessary to determine if underutilization of other health care services is associated with South Asians’ longer hospital stays for digestive diseases.

A longitudinal study found little evidence that immigrants have less access to health care, compared with the Canadian-born, in terms of having a regular doctor or reporting an unmet health care need.^Note 30  Less hospital use by immigrants likely reflects a dominant observation in health research—namely, immigrants tend to be healthier than the Canadian-born population,^{Note 31, Note 32} especially  when they arrive.  This has been attributed to the medical screening required before admission to Canada,^Note 33 and to self-selectivity (individuals willing to undertake the complications and personal disruption involved in immigrating are likely to be relatively healthy).^Note 22  An important exception would be refugees admitted on humanitarian grounds, who are not denied entry because of medical conditions.^{Note 33, Note 34}

Research in the United States and Europe has generally shown higher hospitalization among immigrant seniors, compared with locally born populations.^Note 35-37 A factor associated with higher hospitalization in the American studies was the lack of health insurance among immigrant seniors;^Note 38 European studies tend to include foreign-born respondents regardless of legal status.  Immigrants to many European countries came because of geographic proximity, cultural similarity, war situations, and job opportunities, and thus, could be quite different from immigrants to Canada.^Note 39 These factors could help explaining international differences in hospitalization rates among immigrant seniors.

The present study demonstrates the importance of considering world region of origin, duration and disease-specific effects in determining the health care needs of immigrant seniors. For example, immigrants from East Asia were less likely than Canadian-born seniors to be hospitalized, particularly for circulatory diseases. By contrast, South Asians’ odds of circulatory disease hospitalization did not differ significantly from those of Canadian-born seniors, which is consistent with the higher risk of circulatory diseases among South Asians.^{Note 32, Note 40, Note 41}

The analysis has a number of limitations. The 2006 Census did not collect information about immigration class (economic, family or refugee), which may be important for health service use.  Another limitation is the lack of data about risk factors, such as nutrition, smoking, and alcohol consumption. Smoking, for example, would be important in explaining differences in circulatory disease hospitalizations. The 2006 Census covered only the community-based population, and therefore, offers no information about hospitalization among institutionalized seniors.

Conclusion

This study is a first look at hospital service use access and intensity among immigrant seniors in Ontario.  The linked data have several advantages.  First, the use of administrative data removes potential recall bias^Note 42 and linguistic and cultural barriers that may affect self-reported survey data.^Note 24  Second, the sample size of the census and the availability of information about immigrant origins and period of arrival offer opportunities to examine differences within the immigrant population. Finally, the  covariates available in the census  permit a better understanding of differences in the hospital use of the immigrant and Canadian-born populations.  Such understanding is valuable to health care planners. In the future, this analysis could be extended beyond Ontario to other Canadian jurisdictions for inter-provincial comparisons and to other outcomes, such as the cost of hospital services.

Acknowledgements

The authors thank Olive Collaco and Elsa Ho of the Ontario Ministry of Health and Long-term Care for their assistance in reviewing an earlier version of this paper. Dr. Jack Tu is supported by a Canada Research Chair in Health Services Research and a Career Investigator Award from the Heart and Stroke Foundation–Ontario.