Northwest Tribal Registry Data Assessment – One-page Summary
IDEA-NW/Tribal Registry Project, NPAIHB
June, 2012
The purpose of this evaluation was to assess the representativeness of the Northwest Tribal Registry, ninth version
(NTR9). The NTR is used routinely for record linkages with various health-related surveillance systems (e.g., cancer
registries and death certificates) to identify and correct AI/AN racial misclassification. We wished to assess how well this
data source represented the AI/AN resident population of Idaho, Oregon, and Washington; and to identify subpopulations that may be targeted for inclusion in order to provide the most accurate health status data for all Northwest
AI/ANs.
The NTR9 was created in June, 2011 from a combination of 3 source data sets:
 Portland Area IHS Area-wide Patient Registration File, obtained 04/20/2011 (all patients ever registered at a
clinic that was on RPMS at the time of the data pull, and to which the Area Office had direct access)
 Seattle Indian Health Board patient registration (AI/AN patients registered 01/01/2007 – 05/31/2011)
 Patient registration file from one Washington tribe. This clinic does not use RPMS, thus data from these patients
were not available through the Area Office (active patients as of 06/23/2011)
Comparison data sources
 Bridged-race population estimates, 2009, from CDC/NCHS (primary source used)
 U.S. Census intercensal population estimates of AI/AN race alone, 2009
 American Community Survey, 2009 population estimates of AI/AN race alone (for urban population measures)
 2011 Indian Health Service (IHS) User Population numbers by service unit
Key findings
 Among data elements important to this evaluation and to record linkage activities, missing data were relatively
rare. Over 90% of records were found to be residents of Idaho, Oregon, or Washington. There were
proportionally slightly more females in the NTR9 (51.5%) compared to NCHS population estimates (49.5% of
AI/AN Northwest population).

Proportionally, 76.2% of the Northwest NCHS AI/AN population estimate was represented in the NTR9.
Statewide, Oregon AI/ANs appeared to be the least well represented (66% of NCHS estimate represented in
NTR9), followed by Idaho (79%) and Washington (81%).

Younger age groups – most notably children ages 0-9 – were severely under-represented (ratio = 0.37). This
indicates that linkages with data systems containing substantial numbers of children (e.g., childhood disease
registries or hospitalization data) will less completely identify AI/AN racial misclassification. Most adult age
groups (ages 20-79) were proportionally similar to census-based age distributions.

The NTR9 does not equally represent all tribes/service units in the Northwest; several appear to be represented
fairly well (close to 100%), while others are represented very little or not at all.

Some CHSDA counties were less well represented, which may be correlated with characteristics of health system
delivery for that tribe/area, such as lack of an I/T/U facility or a tribal clinic not using RPMS.

The NTR9 under-represented urban AI/AN populations on the whole, but in some cities the NTR9 populations
closely approximated ACS estimates (e.g., Idaho Falls, Pocatello, Pendleton-Hermiston, and Bellingham). The
three cities with urban Indian clinics remained under-represented: only 33.6% of the Portland-VancouverBeaverton area population was captured in the NTR9, while for Seattle-Bellevue-Tacoma and Spokane the
estimates were 47.1% and 66.5%, respectively.

As expected, the NTR9 better represented AI/ANs in CHSDA areas than non-CHSDA counties, rural areas
compared with urban areas, and tribal and IHS service populations where there is an RPMS-reporting clinic.
These findings are consistent with the sources of our data.
For more information, please see the full NTR9 Evaluation Report, http://www.npaihb.org/epicenter/project/reports/
Contact: Megan Hoopes • Director, IDEA-NW/Tribal Registry Project • NPAIHB • 503-416-3261 • mhoopes@npaihb.org
Tribe/Service Unit Population Comparisons
NTR9 = Ninth version, Northwest Tribal Registry
TRIBE/SERVICE UNIT
Burns Paiute
Chehalis
Coeur d'Alene
Colville
Coos, Lower Umpqua, Siuslaw
Coquille
Cow Creek
Cowlitz
Grand Ronde
Hoh
Jamestown
Kalispel
Klamath
Kootenai
Lower Elwha
Lummi
Makah
Muckleshoot
Nez Perce
Nisqually
Nooksack
NW Band of Shoshone
Port Gamble
Puyallup
Quileute
Quinault
Samish
Sauk-Suiattle
Shoalwater Bay
Shoshone Bannock
Siletz
Skokomish
Snoqualmie
Spokane
Squaxin Island
Stillaguamish
Suquamish
Swinomish
Tulalip
Umatilla
Upper Skagit
Warm Springs
Western Oregon Service Unit
Yakama
NARA
SIHB
Spokane Urban Clinic
Included in
IHS
registration
export? (as
of April,
2011)
Yes
Yes
No
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
Yes
No
No
Yes
Yes
Yes
No
Yes
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
On
RPMS?
Yes
Yes
No
Yes
No
No
Yes
Yes
No
No
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
Yes
UserPop
FY2011
215
1,245
5,014
8,384
778
1,163
2,580
2,422
3,703
30
58
69
2,520
183
856
4,361
2,244
4,402
3,971
1,715
1,086
39
1,531
7,773
674
2,511
593
48
419
6,271
5,207
853
249
1,628
795
125
542
1,233
5,021
3,066
517
5,669
2,790
12,629
-
NTR9 Tribe*
260
558
435
7,522
524
518
1,084
1,823
3,709
160
167
130
1,184
145
394
627
1,968
2,041
2,635
170
1,098
112
102
2,524
610
2,671
594
128
127
4,603
3,926
726
307
1,898
814
145
98
816
3,670
1,730
642
4,731
6,565
-
Percent of
User Pop
represented
122.6%
46.7%
9.0%
90.7%
67.9%
48.5%
45.6%
77.8%
102.7%
484.8%
36.4%
28.8%
42.6%
80.1%
47.8%
14.2%
91.4%
45.4%
70.7%
12.7%
109.4%
339.4%
6.4%
32.3%
91.6%
106.8%
104.0%
200.0%
29.3%
73.5%
75.9%
94.0%
100.0%
115.9%
100.0%
97.3%
17.8%
65.4%
75.2%
56.9%
118.9%
84.1%
52.4%
-
TOTAL
107,182
64,691
* Alive residents of ID, OR, or WA; restricted to date of last update 1/1/2008 or later
** Alive residents of ID, OR, or WA
60.8%
CHSDA
population
estimate
(NCHS)
388
10,452
12,945
13,034
12,363
13,152
19,826
52,271
27,762
843
5,076
10,142
3,504
265
4,233
6,525
4,233
37,056
3,898
19,524
6,525
0
4,827
41,945
5,076
5,120
69,464
14,935
690
6,692
42,703
2,650
52,780
4,521
2,650
12,178
4,827
2,757
12,178
3,185
2,757
18,807
15,973
N/A;
regions
overlap
NTR9
CHSDA
population –
county of
residence**
441
7,852
6,543
14,774
7,604
5,733
11,303
35,799
17,441
214
5,266
4,593
3,895
364
5,052
5,796
5,052
29,669
5,826
20,205
5,796
0
2,281
32,166
5,266
4,862
54,428
11,156
805
9,412
26,114
2,492
40,911
6,260
2,492
8,551
2,281
2,605
8,551
2,758
2,605
16,216
18,918
-
Percent of
CHSDA pop
represented
113.7%
75.1%
50.5%
113.3%
61.5%
43.6%
57.0%
68.5%
62.8%
25.4%
103.7%
45.3%
111.2%
137.4%
119.3%
88.8%
119.3%
80.1%
149.5%
103.5%
88.8%
0.0%
47.3%
76.7%
103.7%
95.0%
78.4%
74.7%
116.7%
140.6%
61.2%
94.0%
77.5%
138.5%
94.0%
70.2%
47.3%
94.5%
70.2%
86.6%
94.5%
86.2%
118.4%
-
N/A; regions
overlap
N/A; regions
overlap