=Paper=
{{Paper
|id=Vol-2323/SKI-Canada-2019-7-7-2
|storemode=property
|title=Exploratory Spatial Analysis of Comorbidities Prevalence in People with Osteoarthritis
|pdfUrl=https://ceur-ws.org/Vol-2323/SKI-Canada-2019-7-7-2.pdf
|volume=Vol-2323
|authors=Xiaoxiao Liu,Rizwan Shahid,Stefania Bertazzon,Nigel Waters,Alka B Patel,Claire EH Barber,Peter Faris,Terrence McDonald,Judy E Seidel,Rajrishi Sharma,Tom Briggs,Deborah A Marshall
}}
==Exploratory Spatial Analysis of Comorbidities Prevalence in People with Osteoarthritis==
https://ceur-ws.org/Vol-2323/SKI-Canada-2019-7-7-2.pdf
Spatial Knowledge and Information Canada, 2019, 7(7), 2
Exploratory spatial analysis of
comorbidities prevalence in people with
osteoarthritis
XIAOXIAO LIU A, RIZWAN SHAHID B,C, STEFANIA BERTAZZON B,D, NIGEL WATERS B, ALKA B PATEL A,C,
CLAIRE EH BARBER A,E, PETER FARIS I, TERRENCE MCDONALD F, JUDY E SEIDEL A,C, RAJRISHI
SHARMA G, TOM BRIGGS H, AND DEBORAH A MARSHALL A
a
Department of Community Health Science, Cumming School of Medicine, University of Calgary, Canada
b
Department of Geography, University of Calgary, Canada
c
Applied Research and Evaluation Services, Alberta Health Services, Canada
d
Department of History, Archaeology, Geography, Fine & Performing Arts, University of Florence, Italy
e
Department of Medicine, Cumming School of Medicine, University of Calgary, Canada
f
Department of Family Medicine, Cumming School of Medicine, University of Calgary, Canada
g
Department of Surgery, Cumming School of Medicine, University of Calgary, Canada
h
Planning and Performance, Alberta Health Services, Canada
i
Research Facilitation Analytics, Foothills Medical Centre, Alberta Health Services, Canada
prevalence of OA is expected to continue
ABSTRACT rising due to an aging population and
increasing rates of obesity, a leading risk
There is limited evidence on the factor for OA (Kopec et al., 2008; Rahman
geographical variation in the prevalence of et al., 2014) Comorbidities are commonly
comorbidities in people with osteoarthritis associated with musculoskeletal conditions
in Alberta. Our study explores the spatial (Briggs et al., 2018), especially among the
pattern of osteoarthritis comorbidities along elderly (Guisado-Clavero et al., 2018), which
the rural-urban continuum. The results greatly increases the disease burden of OA
showed a pattern of higher age-sex (Briggs et al., 2018). Comorbidities have the
standardized prevalence rate of potential to influence routine clinical
osteoarthritis comorbidities in the north practice, healthcare utilization and costs of
and rural areas compared to the south and OA patients (Duffield et al., 2017; Cimmino
urban areas, respectively. Hot spots were et al., 2013; Kim et al., 2011).
identified in the north remote area for The Canadian Medical Association (CMA)
osteoarthritis with two or more and Alberta Health Services (AHS) have a
comorbidities, and osteoarthritis with goal to achieve equitable access to OA care,
chronic obstructive pulmonary disease. This with a focus on patients in rural and remote
study provides information for health care areas (Canadian Medical Association, 2013;
planning to support access to health care Government of Alberta, 2008). Albertans
services. live across urban, rural and remote areas,
creating potential difference in access to
health care. It is of great importance to
1. Introduction examine the geographic variation of
comorbidities among people with OA. Our
Osteoarthritis (OA) is the most common study aims to explore the spatial pattern of
form of arthritis affecting 10% to 15% of comorbidities along the rural-urban
Canadian population and is the leading continuum, and identify the areas with hot
cause of hip and knee joint replacement spots of comorbidities.
surgery (Birtwhistle et al., 2015). The
2 Exploratory Spatial Analysis
2. Methods and Data with only one comorbidity, we further
categorized this group by the type of
comorbidity: OA with only HTN, OA with
2.1 Data sources and case definition
only DEP, OA with only COPD, OA with
Records were extracted from five
only DIAB, OA with only CHF, OA with only
administrative health databases - Alberta
PVD, OA with only MI, and OA with only
Health Care Insurance Plan (AHCIP)
CEVD.
population registry, Discharge Abstract
Database (DAD), Physician Claims Database
(claims), Ambulatory Care Classification 2.3 Age-sex standardized OA-
System (ACCS), and Alberta National comorbidity rate
Ambulatory Care Reporting System The OA cases were stratified by sex and age
(NACRS) (Marshall et al., 2015). Records group (18-35, 35-44, 45-54, 55-65, 65-74,
across the five databases were linked using a 75-85, and >=85 years of age). Direct
unique patient identifier. The ninth and standardization method was applied to
tenth revisions of the International calculate the age-sex standardized OA
Classification of Disease (ICD) codes were comorbidity rates (Boyle & Parkin, 1991).
used to identify OA-related visits. We The Alberta OA prevalence population in
defined OA cases by applying a validated OA 2013 were selected as standard population.
case definition - at least one OA
hospitalization (DAD), or at least two OA 2.3 Geographic area
physician visits (claims) within two years, or Alberta Health Services created 5
at least two OA-related ambulatory care geographic zones for directing operational
visits (ACCS/NACRS) within two years, issues, and 7 rural-urban continuum for the
assuming none of the physicians or purposes of analysis and planning. The
ambulatory care visits had occurred on the rural-urban continuum were created based
same day (Lix et al., 2006; Widdifield et al., on population density and distance from
2013; Kopec et al., 2008; Felson et al., urban centres, including Metro (Calgary and
2000). Edmonton), Moderate Metro influence,
Urban (Grand Prairie, Fort McMurray, Red
2.2 Definitions of comorbidities in Deer, Lethbridge and Medicine Hat),
people with OA Moderate Urban influence, Rural Centre
Based on the literature and expert guidance (Brooks, Canmore et al.), Rural, and Rural
from clinicians, we included a list of 8 Remote. By stratifying the rural-urban
chronic conditions for analysis: continuum by the 5 geographic zones, we
hypertension (HTN), depression (DEP), identified 20 geographic sub-areas (Figure
chronic obstructive pulmonary disease 1) in order to capture potential variation
(COPD), diabetes (DIAB), peripheral associated with both zone and rural-urban
vascular disease (PVD), cerebrovascular continuum (Alberta Health Services and
disease (stroke) (CEVD), myocardial Alberta Health, 2017). The six-digit postal
infarction (MI), and congestive heart failure codes reflecting patient residence were
(CHF). Validated algorithms for each of the extracted for spatial analysis.
selected comorbid conditions were applied
to identify comorbidities (Tonelli et al., 2.4 Spatial analysis
2015). The latitude and longitude of each postal
code was obtained by linking the OA data
The OA cases were grouped by the number and the Postal Code Translator Files
of comorbidities: OA with none of these (Alberta Health, 2013). Spatial analysis in
comorbidities, OA with one of these this study included global Moran’s I
comorbidities, OA with two or more of these (Moran, 1950)(Cliff & Ord, 1973),
comorbidities. With respect to the OA cases incremental spatial autocorrelation (Esri,
2017), and hot spot analysis (Getis & Ord,
Exploratory Spatial Analysis 3
1992; Anselin, 1995). Moran’s I is a basic one comorbidity ranged from 321 per 1,000
measure of spatial autocorrelation, which (Urban-North) to 269 per 1,000 (Rural-
produces a spatial autocorrelation index Centre-North) and for OA with two or more
ranging from 1 (positive spatial comorbidities from 152 per 1,000 (Moderate
autocorrelation) to -1 (negative spatial Urban-North) to 263 per 1,000 (Rural
autocorrelation). Incremental spatial Centre-South). For OA with HTN only, rates
autocorrelation measures the strength of ranged from 101 per 1,000 (Rural-Centre-
spatial autocorrelation by different distance Calgary) to 142 per 1,000 (Moderate-Metro-
band. Hot spot analysis based on the Getis- Calgary), for DEP only 81 per 1,000 (Rural-
Ord Gi* statistic detects spatial patterns of Remote-North) to 143 per 1,000 (Rural-
hot spots. The conceptualization of spatial Centre-Calgary), and for COPD 61 per 1,000
relationship between postal codes in both (Rural-Centre-South) to 126 per 1,000
urban and rural areas were captured by (Rural-Centre-North). In general, the
spatial weight matrix with a fixed distance prevalence rates for OA with comorbidities
band and a minimum number of nearest tend to be higher in the north, compared to
neighbors. The critical value of plus or OA without comorbidities (Figure 2). The
minus 1.96 for Z scores and a p value =0.05 rate of OA with HTN and OA with DEP was
were applied to make decisions regarding higher in the south. OA with COPD only was
accepting or rejecting the null hypothesis. observed to be higher in the north.
The hot spot maps were generated by
interpolating Z scores with the Inverse Global Moran’s I suggested a statistically
Distance Weighting Interpolation. significant spatial autocorrelation for all
comorbidity groups. A spatial weight matrix
3. Results with a fixed distance of 6 km and at least 8
We identified 359,638 OA cases in Alberta nearest neighbors was generated to model
in 2013 (Table 1), of which 52% had at least the spatial relationship of postal codes in
one comorbidity (n=186,350), and 18% had both rural and urban areas. Hot spots
two or more comorbidities (n=120,936). analysis identified hot spots of OA with one
Comorbidities were more frequent in comorbidity in both Rural-North and Rural-
females in all comorbidity groups, South (Figure 3). OA with HTN showed hot
compared to males (23% vs 20% for OA spots in the Moderate Urban area, in both
with at least one of these comorbidities; 8% south and north, and Rural Remote –
vs 7% for OA with two or more Northwest. While for OA with COPD only,
comorbidities). we identified hot spots mostly in Rural
Centre-North, Rural Remote –North, and
Among OA cases with only one comorbidity, Rural Remote –Northwest.
HTN was the most frequent comorbid
condition, accounting for 13% (n=46,871) of 4. Conclusion
total OA cases, followed by DEP (10.6%,
n=38,248), COPD (7%, n=25,495) and We explored the geographic variation in OA
diabetes (2%, n=7,794). CHF, PVD, MI and comorbidities and showed that higher rates
CEVD were identified to be the least of comorbidities in people with OA tend to
frequent comorbid conditions in OA cases, be observed in the north rural areas. The
with the percentage of OA cases ranging findings provide valuable information for
from 0.3% for CHF to 0.04% for CEVD. planning healthcare delivery and informing
Comorbidities with a frequency lower than equitable access to health care. Further
3% were excluded from spatial analysis due research will explore the driving factors
to limited number of cases. influencing this observed variation.
By rural-urban continuum, the age-sex
standardized prevalence rate for OA with
4 Exploratory Spatial Analysis
and the medical profession.
Cimmino, M. A., Scarpa, R., Caporali, R.,
Acknowledgements Parazzini, F., Zaninelli, A., & Sarzi-
Puttini, P. (2013). Body mass and
osteoarthritic pain: results from a
Acknowledge funders.
study in general practice. Clinical and
This work was supported by the Canadian
Experimental Rheumatology, 31, 843–
Institute of Health Research and the Arthur
849. Retrieved from
J.E. Child Chair in Rheumatology Research.
http://www.clinexprheumatol.org/arti
cle.asp?a=6117
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6 Exploratory Spatial Analysis
Table 1 Summary of OA comorbidities
OA Cases (2013)
Comorbidity Type Female Male All Female Male All
n % of OA Cases (2013)
Hypertension (HPTN) 28,186 18,685 46,871 5.7% 5.2% 13.0%
Depression (DEP) 26,695 11,553 38,248 5.4% 3.2% 10.6%
Chronic Obstructive Pulmonary Disease (COPD) 14,812 10,683 25,495 3.0% 3.0% 7.1%
Diabetes (DIAB) 3,655 4,139 7,794 0.7% 1.2% 2.2%
Congestive Heart Failure (CHF) 554 499 1,053 0.1% 0.1% 0.3%
Peripheral Vascular Disease (PVD) 464 550 1,014 0.1% 0.2% 0.3%
Myocardial Infarction (MI) 73 250 323 0.0% 0.1% 0.1%
Cerebrovascular Disease (CEVD) 78 60 138 0.02% 0.02% 0.04%
OA with One Type of Comorbidity 74,517 46,419 120,936 15.0% 12.9% 33.6%
*
OA with Multi-morbid Condition 41,166 24,248 65,414 8.3% 6.7% 18.2%
OA with Comorbidities 115,683 70,667 186,350 23.3% 19.6% 51.8%
OA with No Comorbidities 93,853 79,435 173,288 18.9% 16.0% 48.2%
Total - OA in Alberta 209,536 150,102 359,638 58.3% 41.7% 100.0%
*
Combination of any comorbidity types.
Exploratory Spatial Analysis 7
Figure 1 Geographic areas in Alberta
8 Exploratory Spatial Analysis
Figure 2 Distribution of age-sex standardized rate for OA with one comorbidity, OA with multimorbidity, OA with
HTN only and OA with COPD only, along the rural-urban continuum.
Exploratory Spatial Analysis 9
Figure 3 Hot spots of OA with one comorbidity, OA with multimorbidity, OA with HTN only, and OA with COPD
only.