Transcript Use of Measures of Size in Sample Design and Estimation of Physician Surveys Kennon R.

Use of Measures of Size in Sample Design and
Estimation of Physician Surveys
Kennon R. Copeland
Elizabeth Wallace
IMS Health
June 20, 2007
© 2006 IMS Health Incorporated or its affiliates. All rights reserved.
Outline
• Overview
• Sizing Measures
• Description of Case Study Physician Survey Methodology
• Relationship between Physician Size, Measures of Interest
• Simulated Estimates Utilizing Post-stratification on Physician
Size
• Implications for Sample Design, Estimation
• Summary
ICES III Physician Sizing • June 20, 2007
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Overview
• Physician surveys important in measuring disease,
treatment patterns
 Distribution of diseases
 Drug treatment for diseases
• Sample design for physician surveys typically focuses on
specialty, geography influences
 Information available from AMA Master File
• Physician practice size (e.g., # of patients) may influence
treatment patterns
 Number of treatments
 Types of diseases seen, drug utilization
ICES III Physician Sizing • June 20, 2007
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© 2006 IMS Health Incorporated or its affiliates. All rights reserved.
Sizing Measures in Sample Design, Estimation
• Business survey stratification commonly uses size measures
 Employment, sales, etc.
 Improve design efficiency, avoid biased samples
 Especially when related to propensity to respond
• Ratio estimation using measure of size often used
 Weight based upon relative size of reporting sample
 Can provide variance reduction, “selected sample” bias relief
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Physician Sizing
• Practice size information not available for population
 AMA Master File does provide frame with useful demographic
information on physicians
 Specialty, Type of Practice, Geography, Age
• Prescription volume data are available through pharmacy
sample data
 Rx volume can be viewed as proxy for physician practice size
 IMS Rx sample data encompass roughly three-fourths of all U.S.
prescriptions
 IMS Rx estimates by physician are generated using blended
stratified ratio, geo-spatial estimation approach
ICES III Physician Sizing • June 20, 2007
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Physician Sizing: Study Approach
• Physician measures of size determined by specialty
 9 specialties (Primary care: FP, IM, OBG, PED
Specialists: CD, GE, ONC, ORS, PSY)
 Measure of Size: Rx volume for major drug classes for each
specialty
 Selected classes accounting for at least 5% of specialty Rx volume, with
minimum of 25% of specialty volume accounted for
 Deciles (based on estimated Rx volume) created for each specialty
 Deciles grouped into Low (deciles 1-3), Med (deciles 4-6), High (deciles
7-10)
• Rx volume measures of size examined for two IMS physician
surveys
 Integrated Promotional Services-Office Promotion Report
 National Disease and Therapeutic Index
ICES III Physician Sizing • June 20, 2007
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Physician Sizing: Drug Classes
Drug Classes Used in Physician Sizing
Specialty
Drug Classes
Cardiology (CD)
BETA BLOCKERS
HMG-COA REDUCTASE INHIB
ACE INHIB,ALONE
CALCIUM BLOCKERS
ANTI-PLATELETS,ORAL
HMG-COA REDUCTASE INHIB
BETA BLOCKERS
ACE INHIB,ALONE
SSRI
CODEINE&COMB,NON-INJ
PROTON PUMP INHIB
THYROID HORMONE,SYNTH
PROTON PUMP INHIB
PRE-XRAY EVACUANTS
GI ANTI-INFLAM
HYPEROSMOLAR LAX
HMG-COA REDUCTASE INHIB
BETA BLOCKERS
ACE INHIB,ALONE
PROTON PUMP INHIB
THYROID HORMONE,SYNTH
CALCIUM BLOCKERS
O/C ESTROGEN/PROGESTOGEN
HORMONES,ESTROGENS,ORAL
AROMATASE INHIB
CODEINE&COMB,NON-INJ
ANTINEO ANTIESTROGENS
HORMONES,CORT PLAIN,ORAL
BENZODIAZEPINES
CODEINE&COMB,NON-INJ
ANTIARTH,PLAIN
PROPOXYPHENE
AMINOPENICILLINS
ANALEPTICS
CEPHALOSPORINS & RELATED
EXTENDED SPECTRUM MACROL
SSRI
SEIZURE DISORDERS
BENZODIAZEPINES
NEWER GENERATION ANTIDEP
ANTIPSYCHOTICS,OTH
ANALEPTICS
NON-BARB,OTH
Family Practice (FP)
Gatroenterology (GE)
Internal Medicine (IM)
Obstetrics/Gynecology (OBG)
Oncology (ONC)
Orthopedic Surgery (ORS)
Pediatrics (PED)
Psychiatry (PSY)
ICES III Physician Sizing • June 20, 2007
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% of Specialty Rx Volume
Class
Total
12.9%
10.1%
7.9%
6.0%
5.2%
42.1%
4.9%
3.9%
3.9%
3.7%
3.4%
3.3%
3.2%
26.3%
26.7%
6.7%
5.7%
5.2%
44.3%
5.8%
4.6%
4.1%
3.6%
3.5%
3.4%
25.1%
29.0%
5.4%
34.4%
8.0%
7.1%
3.8%
3.6%
3.3%
25.9%
39.8%
13.6%
5.6%
59.0%
9.3%
5.8%
5.1%
5.0%
25.1%
17.3%
11.8%
9.8%
9.5%
8.9%
6.4%
5.1%
68.9%
© 2006 IMS Health Incorporated or its affiliates. All rights reserved.
Physician Sizing: Deciling
• ~Two-thirds to three-fourths of physicians have “low” volume,
10%-15% have “high” volume, 15%-20% have “med” volume
• Ave Rx volume 5-12 times greater for “high” than for “low”
Physician Rx Volumes
Specialty by Decile (Separate, Grouped)
Source: IMS Xponent, 4Q06
Specialty
CD
FP
GE
IM
OBG
ONC
ORS
PED
PSY
Max TRx
% Phys
Group %
Max TRx
% Phys
Group %
Max TRx
% Phys
Group %
Max TRx
% Phys
Group %
Max TRx
% Phys
Group %
Max TRx
% Phys
Group %
Max TRx
% Phys
Group %
Max TRx
% Phys
Group %
Max TRx
% Phys
Group %
1
468
45.3%
490
51.2%
261
39.4%
478
61.9%
222
48.6%
81
56.0%
150
43.2%
149
53.4%
389
57.9%
ICES III Physician Sizing • June 20, 2007
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2
669
11.8%
66.1%
765
11.0%
70.2%
367
12.9%
62.2%
742
8.6%
76.8%
334
11.9%
69.1%
151
11.8%
75.3%
214
13.2%
66.2%
225
11.3%
73.0%
666
11.8%
77.4%
3
831
8.9%
4
977
7.4%
975
8.0%
1,167
6.5%
447
9.9%
528
8.3%
951
6.2%
1,136
5.1%
428
8.7%
519
7.0%
203
7.6%
258
5.8%
270
9.9%
327
8.0%
289
8.2%
355
6.6%
929
7.7%
1,204
5.8%
Decile
5
6
1,133
1,304
6.4%
5.5%
19.3%
1,349
1,546
5.5%
4.8%
16.8%
615
708
7.1%
6.1%
21.5%
1,321
1,517
4.3%
3.7%
13.1%
610
711
5.8%
5.0%
17.8%
310
362
4.7%
4.0%
14.6%
388
459
6.7%
5.7%
20.4%
430
514
5.4%
4.5%
16.5%
1,508
1,846
4.5%
3.7%
14.0%
7
1,505
4.8%
1,781
4.2%
811
5.3%
1,747
3.2%
829
4.3%
425
3.4%
555
4.8%
629
3.7%
2,238
3.0%
© 2006 IMS Health Incorporated or its affiliates. All rights reserved.
8
9
1,775
2,243
4.1%
3.4%
14.7%
2,079
2,549
3.6%
3.0%
13.0%
958
1,226
4.6%
3.8%
16.3%
2,025
2,473
2.8%
2.4%
10.2%
984
1,242
3.7%
3.0%
13.0%
518
672
2.9%
2.3%
10.1%
697
948
3.9%
3.0%
13.4%
787
1,071
3.0%
2.3%
10.5%
2,785
3,689
2.5%
1.9%
8.6%
10
6,010
2.4%
8,704
2.2%
3,621
2.6%
8,547
1.7%
6,697
2.1%
2,392
1.5%
4,487
1.8%
5,613
1.5%
15,708
1.2%
Physician Survey Methodology:
Office Promotion Report (OPR)
• Office-based physicians, recording information on all
pharmacy rep contacts in reporting period
 Measures of interest
 Contacts
 Details
 Samples
 Panel of physicians
 4,011 per month
 Stratified by 27 group specialties by 43 state groups
(sample design)
 Aggregated into 27 group specialties by 4 regions
(estimation)
 Reporting period
 Full month
ICES III Physician Sizing • June 20, 2007
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Physician Survey Methodology:
National Disease and Therapeutic Index (NDTI)
• Office-based physicians, recording information on all
patient contacts in assigned reporting period
(analogous to NCHS’ NAMCS)
 Measures of interest
 Diagnosis visits
 Drug mentions
 Panel of physicians
 1,373 per month
 4,120 unique per quarter
 Stratified by 108 primary specialties by 9 geographic
divisions (sample design)
 Aggregated into 30 group specialties by 4 geographic
regions (estimation)
 Reporting period
 2 randomly selected, consecutive days per quarter
ICES III Physician Sizing • June 20, 2007
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Relationship between Physician Size, Measures
of Interest: OPR
• Low Decile groups have lowest # of contacts
• High Decile groups generally have highest # of contacts
Median Monthly Contacts per Physician
Specialty Group by Rx Volume Group
Source: IMS OPR, 4Q06
9
Median monthly contacts per physician
8
7
6
CD
FP
GE
IM
OBG
ONC
ORS
PED
PSY
5
4
3
2
1
0
LOW
MED
Decile Rank
ICES III Physician Sizing • June 20, 2007
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HIGH
Relationship between Physician Size, Measures
of Interest: OPR
• Difference between Med, High groups may be due to sample
distribution, variability
 IM shows increasing trend for details, with increased variability
for highest deciles
Median Monthly Contacts per Physician
IM's by Rx Volume Decile
Source: IMS OPR, 4Q06
14
Median monthly contacts per physician
12
10
8
IM
Linear (IM)
6
4
2
0
1
2
3
4
5
6
7
Decile
ICES III Physician Sizing • June 20, 2007
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8
9
10
Relationship between Physician Size, Measures
of Interest: OPR
• Low Decile groups generally have lowest average number of
drug classes detailed
• High Decile groups generally have highest average number
of drug classes detailed
Number of Drug Classes Detailed
Specialty by Decile Group
Source: IMS OPR, 4Q06
Specialty
CD
FP
GE
IM
OBG
ONC
ORS
PED
PSY
ICES III Physician Sizing • June 20, 2007
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Average Drug Classes per Physician
LOW
MED
HIGH
8.2
6.4
10.0
10.4
15.2
17.5
4.0
4.6
6.9
10.3
18.6
18.3
6.1
7.8
7.9
4.1
6.1
9.8
2.4
4.1
3.4
7.1
12.4
12.1
4.2
5.7
7.0
© 2006 IMS Health Incorporated or its affiliates. All rights reserved.
Relationship between Physician Size, Measures
of Interest: NDTI
• Low Decile groups have lowest # of drug appearances
• High Decile groups generally have highest # of drug appearances
Median Monthly Drug Appearances per Physician
Specialty Group x Rx Volume Group
Source: IMS NDTI, 4Q06
Median monthly drug appearances per physician
60
50
40
CD
FP
GE
IM
OBG
ONC
ORS
PED
PSY
30
20
10
0
LOW
MED
Decile Rank
ICES III Physician Sizing • June 20, 2007
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HIGH
Relationship between Physician Size, Measures
of Interest: NDTI
• Low Decile groups generally have lowest # of diagnosis visits
• High Decile groups generally have similar to slightly higher # of
diagnosis visits as Med groups
Mean Monthly Diagnosis Visits per Physician
Specialty Group x Rx Volume Group
Source: IMS NDTI, 4Q06
Mean monthly diagnosis visits per physician
30
25
CD
FP
GE
IM
OBG
ONC
ORS
PED
PSY
20
15
10
5
0
LOW
MED
Decile Rank
ICES III Physician Sizing • June 20, 2007
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HIGH
Simulated Estimates Utilizing Post-stratification
on Physician Size: OPR
• Post-stratify OPR sample based on Rx volume
 Low, Med, High decile groups
• Weight based upon reporting sample coverage
 Population to sample physicians within specialty stratum
• Compare estimates, variances with those from specialty level
weighting
ICES III Physician Sizing • June 20, 2007
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Simulated Estimates Utilizing Post-stratification
on Physician Size: OPR
• Sample distributions often do not mirror population distributions
Physician Population, Sample Distribution
Specialty by Decile Group
Source: IMS OPR, Dec 2006
Physician
Rx Decile Group
Distribution
Low
Med
High
CD
Population
61.4%
21.8%
16.9%
Sample
62.6%
25.9%
11.5%
FP
Population
62.9%
20.8%
16.4%
Sample
50.1%
29.9%
20.0%
GE
Population
57.9%
24.1%
18.1%
Sample
50.8%
34.4%
14.8%
IM
Population
68.0%
17.7%
14.2%
Sample
64.2%
20.3%
15.4%
OBG
Population
62.1%
23.7%
14.3%
Sample
60.6%
21.2%
18.2%
ONC
Population
72.3%
16.2%
11.5%
Sample
78.9%
12.2%
8.9%
ORS
Population
60.4%
23.4%
16.1%
Sample
64.4%
26.4%
9.2%
PED
Population
67.4%
19.7%
12.9%
Sample
57.9%
24.2%
17.9%
PSY
Population
72.5%
16.5%
11.0%
Sample
67.5%
21.7%
10.8%
Yellow shaded boxes indicate sample distribution 5+ percentage point deviation
from population distribution
Specialty
ICES III Physician Sizing • June 20, 2007
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Simulated Estimates Utilizing Post-stratification
on Physician Size: OPR
• Post-stratification by size yields noticeably larger estimates,
slightly smaller relative variances
Estimated Contacts
By Specialty
4Q06
Specialty
CD
FP
GE
IM
OBG
ONC
ORS
PED
PSY
Month
Oct 06
Nov 06
Dec 06
Oct 06
Nov 06
Dec 06
Oct 06
Nov 06
Dec 06
Oct 06
Nov 06
Dec 06
Oct 06
Nov 06
Dec 06
Oct 06
Nov 06
Dec 06
Oct 06
Nov 06
Dec 06
Oct 06
Nov 06
Dec 06
Oct 06
Nov 06
Dec 06
ICES III Physician Sizing • June 20, 2007
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Current
(Specialty Only)
157,920
131,672
101,053
573,786
479,125
378,200
48,085
42,054
34,804
622,572
584,373
492,768
177,878
160,930
118,384
29,120
23,532
15,100
45,938
39,936
34,830
255,190
247,707
199,554
168,960
154,679
109,368
Estimated Details
Size Poststratification
174,356
143,616
113,595
600,544
501,854
389,442
54,408
47,339
39,591
730,874
691,442
573,330
182,706
166,572
123,157
41,986
33,683
20,530
51,430
41,977
38,570
275,692
263,212
214,379
177,279
153,834
110,443
Rel Diff
10.4%
9.1%
12.4%
4.7%
4.7%
3.0%
13.1%
12.6%
13.8%
17.4%
18.3%
16.3%
2.7%
3.5%
4.0%
44.2%
43.1%
36.0%
12.0%
5.1%
10.7%
8.0%
6.3%
7.4%
4.9%
-0.5%
1.0%
CV for Estimated Details
Current
Size Post(Specialty Only)
stratification
14.8%
14.6%
13.4%
12.9%
14.8%
14.3%
6.0%
5.8%
6.2%
5.7%
6.1%
5.6%
15.0%
15.1%
16.0%
15.8%
15.1%
14.4%
6.5%
5.5%
6.1%
5.3%
7.3%
6.2%
7.4%
7.4%
6.9%
6.8%
7.4%
7.6%
19.5%
17.8%
24.2%
23.2%
19.1%
16.3%
12.5%
12.1%
12.2%
10.9%
13.1%
11.2%
6.5%
6.1%
6.8%
6.3%
6.7%
6.1%
8.7%
7.3%
7.8%
6.8%
8.1%
7.1%
© 2006 IMS Health Incorporated or its affiliates. All rights reserved.
Simulated Estimates Utilizing Post-stratification
on Physician Size: OPR
• Relative variances greater for High volume physicians
CVs for Estimated Details
By Specialty Decile Group
4Q06
Specialty
CD
FP
GE
IM
OBG
ONC
ORS
PED
PSY
ICES III Physician Sizing • June 20, 2007
19
Decile Group
Low
Med
High
Low
Med
High
Low
Med
High
Low
Med
High
Low
Med
High
Low
Med
High
Low
Med
High
Low
Med
High
Low
Med
High
Median CV
Size Poststratification
19.8%
18.8%
28.4%
7.8%
10.7%
11.9%
19.5%
22.5%
39.3%
7.7%
10.0%
10.9%
9.6%
11.5%
17.3%
16.0%
33.3%
43.5%
12.3%
23.9%
22.8%
9.6%
9.2%
13.1%
7.6%
14.1%
18.7%
© 2006 IMS Health Incorporated or its affiliates. All rights reserved.
Implications for OPR Sample Design, Estimation
• Optimal sample allocation could reduce estimate variance
 Requires re-allocation of existing sample distribution
 Especially for specialists, less so for primary care
Physician Rx Sample Allocation
Within Specialty by Decile Group
Current=Dec '06 OPR
Specialty
Group %
CD
Current
Optimal
Proportional
Optimal
Proportional
Optimal
Proportional
Optimal
Proportional
Optimal
Proportional
Optimal
Proportional
Optimal
Proportional
Optimal
Proportional
Optimal
FP
GE
IM
OBG
ONC
ORS
PED
PSY
ICES III Physician Sizing • June 20, 2007
20
Low
62.6%
63.4%
50.1%
65.7%
50.8%
52.8%
60.6%
64.2%
62.1%
64.5%
78.9%
33.8%
64.4%
39.6%
57.9%
70.0%
67.5%
53.2%
Decile Group
Med
25.9%
12.6%
29.9%
15.6%
34.4%
15.4%
21.2%
20.0%
23.7%
16.0%
12.2%
25.3%
26.4%
31.9%
24.2%
17.9%
21.7%
20.0%
© 2006 IMS Health Incorporated or its affiliates. All rights reserved.
High
11.5%
24.0%
20.0%
18.7%
14.8%
31.8%
18.2%
15.8%
14.3%
19.5%
8.9%
40.9%
9.2%
28.5%
17.9%
12.1%
10.8%
26.7%
Summary
• Physician Rx volume appears to be usable proxy for
physician practice size
 Physician Rx volume related to productivity
• Incorporating physician Rx volume into sample design can
yield improved estimates
 Physician Rx volume can vary dramatically
 Stratification should account for physician Rx volume
 Optimal allocation can control variability
ICES III Physician Sizing • June 20, 2007
21
© 2006 IMS Health Incorporated or its affiliates. All rights reserved.
Future Development
• Examine relationship between Rx volume, treatment
patterns
 e.g., Drug distribution
• Consider regrouping deciles
 Population size likely supports splitting Low into Decile 1, Deciles
2-4
 Examine efficiency gains
• Explore predominant drug classes vs total Rx volume
 Total treatments/contacts vs distribution of treatments/contacts
• Explore use of Rx volume as measure of size in ratio
estimation
 For large Rx volume group, may control for skewed sample
ICES III Physician Sizing • June 20, 2007
22
© 2006 IMS Health Incorporated or its affiliates. All rights reserved.