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NPJ Parkinson's Disease logoLink to NPJ Parkinson's Disease
. 2019 Jan 24;5:1. doi: 10.1038/s41531-019-0074-8

State-level prevalence, health service use, and spending vary widely among Medicare beneficiaries with Parkinson disease

Sneha Mantri 1,2,#, Michelle E Fullard 2,✉,#, James Beck 3, Allison W Willis 2,4,5
PMCID: PMC6345811  PMID: 30701188

Abstract

State-level variations in disease, healthcare utilization, and spending influence healthcare planning at federal and state levels and should be examined to understand national disparities in health outcomes. This descriptive study examined state-level variations in Parkinson disease (PD) prevalence, patient characteristics, Medicare spending, out-of-pocket costs, and health service utilization using data on 27.5 million Medicare beneficiaries in the US in 2014. We found that 45.8% (n = 179,496) of Medicare beneficiaries diagnosed with PD were women; 26.1% (n = 102,205) were aged 85+. The District of Columbia, New York, Illinois, Connecticut, and Florida had the highest age-, race-, and sex-adjusted prevalence of Parkinson disease among Medicare beneficiaries in the US. Women comprised over 48.5% of PD patient populations in West Virginia, Kentucky, Mississippi, Louisiana, and Arkansas. More than 31% of the PD populations in Connecticut, Pennsylvania, Hawaii, and Rhode Island were aged 85+. PD patients who were “dual-eligible”—receiving both Medicare and Medicaid benefits—also varied by state, from <10% to >25%. Hospitalizations varied from 304 to 653 stays per 1000 PD patients and accounted for 26.5% of the 7.9 billion United States Dollars (USD) paid by the Medicare program for healthcare services delivered to our sample. A diagnosis of PD was associated with greater healthcare use and spending. This study provides initial evidence of substantial geographic variation in PD patient characteristics, health service use, and spending. Further study is necessary to inform the development of state- and federal-level health policies that are cost-efficient and support desired outcomes for PD patients.

Healthcare provision: Geographical variation across the United States

Analyses of the prevalence of Parkinson’s disease (PD), health service spending and use reveal significant disparities between different American states. Michelle Fullard at the University of Pennsylvania and colleagues examined data from 27.5 million over-65-year olds covered by national health insurance in the USA (Medicare). In 2014, Medicare spent nearly 7.9 billion USD on health care services for patients with PD, but the states with highest PD prevalence (District of Columbia, New York, and Illinois) did not always correlate with those registering the highest number of hospitalizations (New York, Michigan, and Illinois) or highest spending on healthcare provision for PD patients (Nevada, Texas, and Massachusetts). This type of study is becoming increasingly important to inform healthcare planning in countries with aging populations in which the prevalence of neurodegenerative diseases such as PD is steadily rising.

Introduction

State-level variation in disease prevalence,1,2 health care utilization, spending/costs,3,4 healthcare quality,5 and clinical outcomes6–10 have been observed among Medicare beneficiaries. These data have driven health care reform initiatives and influenced health care planning at federal and state levels, in attempts to normalize spending and reduce inequity in care and outcomes. In the US, health care and reimbursement are increasingly governed at the state level. For instance, Medicare11 is a federally administered program providing health insurance to individuals over the age of 65, while Medicaid, which provides coverage to individuals below the poverty line, is funded by individual states.11 Persons covered by both programs are termed “dual-eligibles”. Medicare beneficiaries who are dual-eligible and have a neurodegenerative disease, like Parkinson disease (PD), have often qualified for Medicaid due to loss of wealth from health care expenses and/or long-term care services. For dual-eligible individuals over the age of 65, Medicare remains the primary payer for office visits, hospitalizations, home health, and skilled nursing facility care; Medicaid assists with remaining costs of care.

PD is a common neurodegenerative condition marked by sociodemographic disparities in care and outcomes.12–14 However, there are limited population-level data on geographic variations in PD, and no data on how PD care and spending differ across the US. With the increasing prevalence of PD in the US, health care needs and costs will also increase, so population-level data is needed to inform health policy and planning at the state and federal level to address these changing needs. To address these gaps in knowledge, this descriptive study examined state-level variation in PD prevalence among US Medicare beneficiaries. We also examined state-level variations in PD patient characteristics, Medicare spending, out-of-pocket health care costs, and health service utilization. These data are useful for targeting areas in which PD patients may have increased need and can be used to evaluate the effects of future changes in Medicare and Medicaid policies on persons with PD.

Results

Variation in PD prevalence and characteristics

We identified 27,538,023 Medicare beneficiaries that met our inclusion criteria, of whom 392,214 had a PD diagnosis in 2014. State-level variation in the prevalence of PD per 100,000 Medicare individuals is shown in Table 1 and Fig. 1. Crude prevalence varied from 845/100,000 in Minnesota to 1781/100,000 in New York. The top five states—New York, Connecticut, Florida, Pennsylvania, and Rhode Island—contained 20.7% of all Medicare beneficiaries diagnosed with PD in our sample. After adjusting for baseline differences in race, age, and sex, New York, Illinois, Connecticut, Florida, Pennsylvania, and Rhode Island remained the states with the highest prevalence.

Table 1.

PD prevalence and demographic characteristics among Medicare beneficiaries, by state

Medicare beneficiaries total, n PD, n Crude prevalence per 100,000 (95% CI) Age, race, sex adjusted PD prevalence (per 100,000)a Adjusted PD prevalence rank % Female Rank % female % 65–69 % 70–74 % 75–79 % 80–84 % 85+ Rank % 85+ % Dual eligible Rank % dual eligible
Alabama 512,181 7138 1393.64 (1361.81, 1426.02) 1459.18 14 46.7% 14 13.4% 19.8% 23.9% 21.9% 21.0% 45 18.6% 19
Alaska 59,735 604 1011.13 (933.25, 1093.75) 1086.54 47 38.6% 51 17.7% 24.8% 23.3% 17.4% 16.7% 51 22.7% 10
Arizona 529,547 6676 1260.70 (1230.91, 1291.01) 1279.80 33 39.7% 48 14.5% 20.3% 23.1% 20.7% 21.3% 43 9.2% 48
Arkansas 343,037 4415 1287.03 (1249.72, 1325.16) 1288.81 32 48.6% 5 12.5% 19.7% 23.4% 22.3% 22.0% 37 23.5% 7
California 2,248,672 34,101 1516.49 (1500.58, 1532.40) 1520.10 10 44.9% 29 12.2% 17.6% 20.9% 21.7% 27.6% 12 28.7% 2
Colorado 372,747 4524 1213.69 (1178.91, 1249.22) 1237.98 38 40.9% 47 15.1% 19.5% 21.1% 20.5% 23.8% 28 15.5% 29
Connecticut 350,160 5904 1686.08 (1643.84, 1729.13) 1560.43 4 46.2% 17 10.3% 15.3% 19.0% 22.3% 33.2% 1 25.7% 5
Delaware 126,971 1560 1228.62 (1169.14, 1290.33) 1272.21 36 43.1% 38 14.7% 19.9% 22.7% 21.5% 21.3% 42 15.3% 31
District of Columbia 52,694 646 1225.94 (1134.64, 1322.60) 1747.75 1 45.5% 25 12.4% 17.3% 22.6% 21.5% 26.2% 20 29.7% 1
Florida 1,875,551 30,653 1634.34 (1616.27, 1652.41) 1551.08 5 44.8% 31 10.5% 16.8% 21.8% 22.7% 28.2% 9 23.3% 9
Georgia 745,589 9251 1240.76 (1215.82, 1265.96) 1322.34 25 45.7% 23 13.1% 20.1% 23.6% 21.9% 21.3% 41 18.9% 18
Hawaii 89,335 1114 1246.99 (1175.79, 1321.34) 1265.80 37 45.6% 24 11.6% 16.3% 19.1% 21.7% 31.2% 3 12.0% 37
Idaho 141,265 1594 1128.37 (1074.29, 1184.46) 1129.67 43 42.3% 42 11.7% 19.1% 24.7% 22.2% 22.3% 35 16.8% 24
Illinois 1,236,916 19,466 1573.75 (1551.93, 1595.63) 1566.12 3 45.5% 26 11.5% 16.8% 21.4% 22.3% 28.0% 10 11.2% 41
Indiana 655,313 9751 1487.99 (1458.89, 1517.34) 1472.26 12 47.6% 9 12.7% 17.3% 22.5% 22.1% 25.4% 22 24.3% 6
Iowa 395,093 5504 1393.08 (1356.89, 1429.82) 1323.44 24 44.7% 32 12.4% 17.3% 22.2% 22.3% 25.8% 21 17.6% 20
Kansas 323,255 4977 1539.65 (1497.64, 1582.53) 1455.60 15 46.1% 18 12.2% 16.1% 20.9% 22.1% 28.7% 8 17.5% 21
Kentucky 432,696 6154 1422.24 (1387.28, 1457.85) 1432.57 18 49.3% 2 13.6% 18.3% 23.1% 21.8% 23.2% 31 20.1% 16
Louisiana 381,276 5466 1433.60 (1396.24, 1471.70) 1518.47 11 48.9% 4 13.4% 18.8% 23.1% 22.9% 21.8% 38 21.9% 12
Maine 168,276 2187 1299.65 (1246.37, 1354.60) 1237.83 39 44.4% 34 11.9% 17.4% 20.4% 22.7% 27.6% 13 26.0% 4
Maryland 651,007 8612 1322.87 (1295.33, 1350.84) 1414.82 20 46.5% 15 12.6% 18.0% 22.0% 21.1% 26.3% 19 15.5% 30
Massachusetts 675,050 9879 1463.44 (1435.00, 1492.13) 1420.75 19 45.0% 28 12.3% 17.4% 20.2% 21.4% 28.8% 7 15.9% 27
Michigan 928,374 13,097 1410.74 (1386.90, 1434.74) 1397.62 22 45.9% 20 12.0% 17.7% 21.0% 21.9% 27.4% 15 11.9% 39
Minnesota 548,458 4635 845.09 (821.12, 869.56) 802.88 51 42.1% 43 10.6% 16.4% 20.5% 24.7% 27.7% 11 5.2% 50
Mississippi 337,839 4130 1222.47 (1185.83, 1259.94) 1312.87 26 49.1% 3 13.7% 19.9% 24.3% 22.7% 19.4% 49 27.3% 3
Missouri 593,862 8745 1472.56 (1442.16, 1503.43) 1443.32 16 46.5% 16 12.9% 18.5% 21.7% 21.9% 25.0% 23 11.0% 42
Montana 127,884 1328 1038.44 (983.98, 1095.11) 1089.36 46 38.9% 50 15.3% 19.3% 22.1% 21.1% 22.3% 36 10.8% 43
Nebraska 217,187 3214 1479.83 (1429.69, 1531.26) 1403.70 21 43.7% 36 11.6% 16.7% 21.8% 22.4% 27.5% 14 10.2% 45
Nevada 214,117 2598 1213.35 (1167.63, 1260.39) 1306.13 28 43.4% 37 15.7% 22.0% 24.0% 19.5% 18.8% 50 17.3% 22
New Hampshire 180,003 2405 1336.08 (1283.82, 1389.91) 1297.98 30 41.7% 44 13.6% 18.9% 21.9% 21.7% 23.9% 26 6.1% 49
New Jersey 946,172 14,871 1571.70 (1546.78, 1596.91) 1541.23 8 45.9% 21 11.2% 17.1% 20.6% 22.2% 28.9% 6 17.0% 23
New Mexico 175,502 1805 1028.47 (982.08, 1076.49) 1010.21 49 42.8% 40 14.0% 19.0% 24.8% 22.3% 19.9% 48 20.4% 15
New York 1,468,850 26,160 1780.98 (1759.69, 1802.27) 1719.80 2 47.5% 10 11.2% 15.7% 20.4% 22.2% 30.5% 5 19.7% 17
North Carolina 907,156 11,008 1213.46 (1191.08, 1236.04) 1291.97 31 45.8% 22 13.8% 19.5% 22.5% 21.7% 22.6% 34 21.3% 13
North Dakota 93,148 1180 1266.80 (1196.48, 1340.14) 1122.78 44 44.9% 30 11.1% 16.4% 21.6% 24.0% 26.9% 16 4.3% 51
Ohio 928,421 13,485 1452.46 (1428.28, 1476.80) 1439.76 17 47.1% 11 13.0% 17.5% 21.6% 21.3% 26.6% 18 23.4% 8
Oklahoma 413,847 5045 1219.04 (1185.95, 1252.82) 1222.55 40 47.0% 12 13.7% 18.6% 24.0% 22.0% 21.7% 39 13.9% 33
Oregon 299,606 3331 1111.79 (1074.71, 1149.81) 1151.28 42 41.2% 46 15.0% 21.0% 22.4% 18.6% 23.1% 32 12.0% 38
Pennsylvania 1,080,256 17,272 1598.88 (1575.35, 1622.66) 1549.18 6 48.2% 7 11.6% 15.5% 20.1% 21.4% 31.2% 2 12.7% 35
Rhode Island 81,781 1288 1574.93 (1491.31, 1661.99) 1543.40 7 48.2% 8 13.4% 15.1% 19.3% 21.0% 31.1% 4 11.5% 40
South Carolina 540,745 6371 1178.18 (1149.69, 1207.20) 1274.95 35 46.0% 19 15.2% 20.8% 22.4% 20.9% 20.6% 46 13.1% 34
South Dakota 116,221 1352 1163.30 (1102.86, 1226.17) 1053.87 48 44.0% 35 13.4% 17.4% 23.4% 22.1% 23.7% 30 10.3% 44
Tennessee 597,675 8595 1438.07 (1408.12, 1468.32) 1466.00 13 48.4% 6 13.7% 19.2% 22.2% 22.1% 22.9% 33 16.3% 25
Texas 1,859,155 28,075 1510.09 (1492.63, 1527.57) 1521.95 9 46.8% 13 12.8% 18.7% 22.3% 22.1% 24.1% 24 20.5% 14
Utah 165,047 2232 1352.34 (1297.46, 1408.92) 1299.46 29 39.2% 49 12.7% 20.3% 24.6% 22.3% 20.1% 47 9.8% 46
Vermont 90,310 1035 1146.05 (1078.18, 1217.04) 1120.26 45 42.9% 39 12.5% 18.7% 23.0% 22.0% 23.8% 27 16.2% 26
Virginia 838,962 10,990 1309.95 (1285.78, 1334.32) 1366.83 23 44.6% 33 12.8% 19.1% 22.0% 22.4% 23.7% 29 12.7% 36
Washington 599,741 7424 1237.86 (1210.11, 1266.08) 1215.55 41 42.5% 41 12.4% 19.6% 22.6% 21.4% 23.9% 25 15.9% 28
West Virginia 216,202 2745 1269.64 (1223.10, 1317.49) 1307.36 27 49.9% 1 15.3% 19.6% 23.9% 20.0% 21.1% 44 22.2% 11
Wisconsin 532,630 6960 1306.72 (1276.48, 1337.48) 1279.27 34 45.5% 27 13.0% 16.6% 21.5% 22.2% 26.8% 17 9.6% 47
Wyoming 72,506 662 913.02 (845.73, 984.23) 883.63 50 41.5% 45 14.4% 21.8% 21.1% 21.3% 21.5% 40 14.2% 32
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aAge-, race-, and sex-adjusted prevalence of PD using the direct method of standardization. Standard population was total Medicare beneficiary population

Fig. 1.

Fig. 1

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Prevalence of Parkinson’s disease and characteristics of individuals with PD by state. a Prevalence of Parkinson’s disease (per 100,000), adjusted for age, race, and sex, among Medicare beneficiaries in 2014. b Percentage of Medicare PD population that is dual-eligible. c Percentage of Medicare PD population that is female. d Percentage of Medicare PD population aged 85 years and older. Data are shown in quartiles

State-level estimates of PD prevalence among adults aged 45 years and older were considerably lower, ranging from 450/100,000 in Alaska to 668/100,000 in Florida. Prevalence estimates between the two samples were most similar in Wyoming, New Mexico, Montana, Oregon, and Idaho, all states with very low prevalence in general. In states with the greatest number of Medicare beneficiaries (New York, Texas, Connecticut, Illinois, and New Jersey), Medicare prevalence estimates were more than 2.25 times greater than estimates which included younger individuals (e-Table 1).

Nationally, 45.8% (n = 179,496) of individuals diagnosed with PD in our Medicare dataset were women, and 26.1% (n = 102,205) were aged 85 and above. West Virginia, Kentucky, Mississippi, Louisiana, and Arkansas had the largest proportions of PD patients who were women, over 48.5% of their state PD populations. The proportion of PD patients over the age of 85 was greatest in Connecticut (33.2%), Pennsylvania (31.2%), Hawaii (31.2%), and Rhode Island (31.1%). In contrast, less than 19% of the PD populations in Alaska and Nevada were in the oldest age group. The percentage of individuals diagnosed with PD who were dual-eligible similarly varied by state, from <10% in North Dakota, Minnesota, New Hampshire, Arizona, Wisconsin, and Utah, to >25% in Connecticut, Maine, Mississippi, California, and the District of Columbia (Fig. 1).

Health care utilization

In the year 2014, our Medicare PD sample had 219,049 hospitalizations (558 per 1000 PD); 37,839 readmissions (172 per 1000 hospitalizations); 3,699,767 outpatient physician office visits (9433 per 1000 PD); 34,159 hospice stays (87 per 1000 PD); 113,027 skilled nursing facility stays (288 per 1000 PD); 466,160 emergency room visits (1188 per 1000 PD), of which 39.0% resulted in hospital admission; 1,308,934 durable medical equipment events (3337 per 1000 PD); 6,676,119 laboratory tests (17,021 per 1000 PD); 2,435,654 imaging events (6210 per 1000 PD); and 4,879,538 home health visits (12,441 per 1000 PD). The portion of our sample that had prescription coverage had 16.5 million prescription events.

As shown in Table 2 and Fig. 2, Medicare beneficiaries with PD in Hawaii, Alaska, Utah, North Dakota, and Idaho had the lowest per capita number of hospitalizations (from 304 to 384 per 1000 PD). This was nearly half the hospitalization per capita rate found in New York, Michigan, Illinois, West Virginia, and Florida (624–653 hospital stays per 1000 PD). Thirty-day readmissions have become an increasingly used metric for performance evaluations and reimbursement guidelines. The readmission rate, which varied less by state, was highest in Florida (127 per 1000 hospitalizations), and greater than 115 per 1000 hospitalizations in the District of Columbia, New York, Michigan, and Arkansas. The lowest readmission rates per capita (less than 50 per 1000 hospitalizations) were found in Utah, North Dakota, South Dakota, Alaska, and Hawaii.

Table 2.

State-level health care utilization among Medicare beneficiaries diagnosed with PD, 2014

State name PD Acute inpatient stays Readmissions Emergency department visit with admission Emergency department visit without admission Emergency department admission
n n Per 1000 PD patients Rank n Per 10000 hospitalized PD patients Rank n Per 1000 PD patients Rank n Per 1000 PD patients Rank % Rank
Alabama 7138 3996 560 20 626 88 28 3277 459 22 3646 511 35 47.3 15
Alaska 604 206 341 50 26 43 50 125 207 50 387 641 32 24.4 36
Arizona 6676 2952 442 41 448 67 39 2326 348 36 4299 644 31 35.1 25
Arkansas 4415 2730 618 7 513 116 5 2143 485 13 16,078 3642 4 11.8 48
California 34,101 17,818 523 29 3224 95 21 15,366 451 24 7347 215 45 67.7 6
Colorado 4524 1907 422 43 229 51 46 1480 327 37 801 177 49 64.9 8
Connecticut 5904 3358 569 17 582 99 18 3044 516 9 20,459 3465 5 13.0 45
Delaware 1560 835 535 25 120 77 32 722 463 19 2008 1287 15 26.4 32
District of Columbia 646 383 593 12 80 124 2 348 539 5 2735 4234 3 11.3 49
Florida 30,653 20,011 653 1 3885 127 1 17,913 584 1 20,166 658 29 47.0 17
Georgia 9251 5054 546 24 867 94 23 4195 453 23 4683 506 36 47.3 16
Hawaii 1114 339 304 51 45 40 51 307 276 46 729 654 30 29.6 28
Idaho 1594 612 384 47 84 53 45 383 240 48 2656 1666 11 12.6 47
Illinois 19,466 12,269 630 3 2139 110 8 10,160 522 7 3641 187 47 73.6 3
Indiana 9751 5418 556 21 869 89 26 4176 428 28 1822 187 48 69.6 4
Iowa 5504 2491 453 39 356 65 41 1601 291 42 4485 815 20 26.3 33
Kansas 4977 2618 526 28 378 76 33 1751 352 35 5295 1064 19 24.9 35
Kentucky 6154 3828 622 6 644 105 12 2987 485 14 546 89 51 84.5 1
Louisiana 5466 3296 603 10 596 109 9 2613 478 16 9194 1682 10 22.1 39
Maine 2187 1159 530 27 215 98 19 861 394 31 5511 2520 6 13.5 44
Maryland 8612 4838 562 19 866 101 15 4233 492 12 11,750 1364 12 26.5 31
Massachusetts 9879 5777 585 14 1026 104 14 5135 520 8 7376 747 24 41.0 19
Michigan 13,097 8250 630 4 1542 118 4 7108 543 4 9662 738 26 42.4 18
Minnesota 4635 2170 468 36 331 71 36 1511 326 38 3446 743 25 30.5 27
Mississippi 4130 2545 616 8 440 107 10 1938 469 17 4786 1159 17 28.8 29
Missouri 8745 5057 578 16 879 101 16 3861 442 26 6785 776 23 36.3 24
Montana 1328 591 445 40 87 66 40 366 276 45 921 694 28 28.4 30
Nebraska 3214 1498 466 37 225 70 38 878 273 47 1334 415 39 39.7 22
Nevada 2598 1380 531 26 261 100 17 1211 466 18 4451 1713 9 21.4 40
New Hampshire 2405 1186 493 32 201 84 29 922 383 32 22,095 9187 1 4.0 50
New Jersey 14,871 9014 606 9 1658 111 7 8235 554 2 3679 247 44 69.1 5
New Mexico 1805 840 465 38 133 74 35 636 352 34 553 306 40 53.5 11
New York 26,160 16,327 624 5 3129 120 3 14,291 546 3 14,039 537 34 50.4 13
North Carolina 11,008 5374 488 34 851 77 31 4509 410 29 4688 426 38 49.0 14
North Dakota 1180 446 378 48 52 44 48 222 188 51 844 715 27 20.8 41
Ohio 13,485 7910 587 13 1406 104 13 6519 483 15 10,690 793 21 37.9 23
Oklahoma 5045 2787 552 23 475 94 22 2250 446 25 6541 1297 13 25.6 34
Oregon 3331 1324 397 45 192 58 42 963 289 43 917 275 42 51.2 12
Pennsylvania 17,272 10,026 580 15 1685 98 20 8827 511 10 4950 287 41 64.1 9
Rhode Island 1288 773 600 11 135 105 11 678 526 6 1019 791 22 40.0 21
South Carolina 6371 3163 496 31 493 77 30 2565 403 30 8260 1296 14 23.7 37
South Dakota 1352 527 390 46 59 44 49 310 229 49 1471 1088 18 17.4 43
Tennessee 8595 4761 554 22 781 91 25 3959 461 21 970 113 50 80.3 2
Texas 28,075 15,779 562 18 2562 91 24 12,951 461 20 7552 269 43 63.2 10
Utah 2232 839 376 49 102 46 47 633 284 44 1231 552 33 34.0 26
Vermont 1035 441 426 42 73 71 37 304 294 41 2091 2020 7 12.7 46
Virginia 10,990 5648 514 30 969 88 27 4835 440 27 2333 212 46 67.5 7
Washington 7424 2957 398 44 423 57 43 2291 309 39 3317 447 37 40.9 20
West Virginia 2745 1789 652 2 314 114 6 1373 500 11 5515 2009 8 19.9 42
Wisconsin 6960 3430 493 33 526 76 34 2563 368 33 8878 1276 16 22.4 38
Wyoming 662 322 486 35 37 56 44 197 298 40 5476 8272 2 3.5 51
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Fig. 2.

Fig. 2

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ER visits and hospitalizations in the PD population by state. a Number of acute inpatient stays, per 1000 PD patients, in Medicare beneficiaries with PD in 2014. b Number of readmissions, per 10,000 hospitalized PD patients, in Medicare beneficiaries with PD in 2014. c Number of ED visits with discharge, per 1000 PD patients, in Medicare beneficiaries with PD in 2014. Data are shown in quartiles

Approximately 7.9 billion United States Dollars (USD) were paid by the Medicare program for health care services delivered to our PD sample in 2014. The costliest services were inpatient care (2.1 billion USD), skilled nursing facility care (1.4 billion USD), hospital outpatient care (881.0 million USD), and home health (776.5 million USD). For all health care services, Medicare and out-of-pocket spending was significantly higher for beneficiaries with PD than for beneficiaries without PD (e-Table 2).

There was significant state and regional variation in per capita CMS and out of pocket costs (Fig. 3 and Table 3). The top five states for CMS spending were Nevada, Texas, Massachusetts, Florida, and New York (all greater than 22,000 USD per beneficiary with PD), almost double what was spent in South Dakota and Hawaii. Beneficiary responsibility is proportional to CMS spending; therefore, states in the top quartile for CMS spending were also in the top quartile for out-of-pocket costs. The highest out-of-pocket costs were in the Great Lakes, northeast, and south-central regions. The lowest costs were in the Pacific Northwest, mountain regions, and parts of the South.

Fig. 3.

Fig. 3

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Medicare spending and out of pocket costs by state. a Mean CMS spending per capita for Medicare beneficiaries with PD, 2014. b Out of pocket costs per Medicare beneficiary with PD, 2014. Data are shown in quartiles

Table 3.

State-level Medicare and beneficiary out of pocket spending among Medicare beneficiaries diagnosed with PD, 2014

State name Spending by payer in 2014 US Dollars
CMS Beneficiary/out of pocket
Mean Std dev. Rank Mean Std dev. Rank
Alabama 17,623 23,830 29 2705 3814 34
Alaska 12,954 22,376 49 2034 2745 50
Arizona 17,447 26,231 31 2433 3337 42
Arkansas 18,707 26,877 23 3025 4474 23
California 22,774 38,562 8 3071 4978 21
Colorado 16,722 25,346 35 2613 3944 36
Connecticut 22,002 31,726 9 3178 4523 14
Delaware 19,495 29,910 21 2956 4061 24
District of Columbia 19,703 36,094 20 3097 4674 19
Florida 23,193 29,918 4 3509 4724 2
Georgia 18,067 27,984 26 2873 4363 28
Hawaii 12,568 22,087 51 1903 2896 51
Idaho 14,839 21,867 44 2369 3420 47
Illinois 21,315 30,363 11 3458 4872 4
Indiana 19,867 28,425 15 3472 4913 3
Iowa 14,262 21,739 45 2566 3490 39
Kansas 17,775 24,855 27 2951 4052 25
Kentucky 18,576 26,232 24 3189 4524 13
Louisiana 22,805 31,423 7 3511 5223 1
Maine 17,657 25,555 28 2814 3650 30
Maryland 19,826 30,968 16 3079 4399 20
Massachusetts 23,323 33,708 3 3130 4570 17
Michigan 20,138 28,494 13 3125 4355 18
Minnesota 16,042 24,007 39 2415 3362 44
Mississippi 20,522 29,278 12 3295 5023 9
Missouri 17,588 24,837 30 2927 3939 26
Montana 14,261 22,294 46 2418 3136 43
Nebraska 16,221 24,359 38 2925 4010 27
Nevada 24,021 38,435 1 3202 5092 12
New Hampshire 20,000 30,846 14 3221 4782 10
New Jersey 22,884 33,858 6 3430 4881 5
New Mexico 17,010 24,964 34 2515 3916 40
New York 22,960 36,240 5 3358 4842 6
North Carolina 15,983 22,996 40 2742 3979 32
North Dakota 13,380 25,279 48 2409 3331 45
Ohio 19,765 28,555 19 3210 4594 11
Oklahoma 19,788 28,698 18 2746 4373 31
Oregon 13,696 21,428 47 2072 2859 49
Pennsylvania 19,816 28,253 17 3151 4368 16
Rhode Island 21,870 31,332 10 3154 4596 15
South Carolina 17,240 25,346 33 2715 4182 33
South Dakota 12,932 20,101 50 2407 3347 46
Tennessee 18,102 25,362 25 3049 4456 22
Texas 23,512 32,617 2 3340 5030 7
Utah 16,691 25,062 36 2326 3475 48
Vermont 15,855 25,053 42 2588 3536 38
Virginia 16,682 25,574 37 2691 3859 35
Washington 15,320 25,069 43 2437 3712 41
West Virginia 19,440 28,263 22 3299 4725 8
Wisconsin 15,919 26,427 41 2613 3768 37
Wyoming 17,407 26,752 32 2865 4116 29
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Discussion

In this descriptive study, we determined that among Medicare beneficiaries, there is significant state-level variation in PD prevalence, demography, dual-eligible status, and spending. States which have a higher prevalence of PD may have a larger proportion of high-risk factor patient groups, a higher concentration of providers who recognize and document PD, increased public awareness of PD symptoms, or increased health care seeking behaviors among people living in the state. Among our top PD prevalence states, Florida and New York also rank high in terms of absolute number of Medicare beneficiaries, and have large supplies of health care providers. Environmental factors, including exposure to exogenous toxicants (such as pesticides,15 heavy metals,16 or solvents17) vary by location and may influence our prevalence estimates by altering the risk of PD or of a PD diagnosis. There are proposed protective factors for PD, such as coffee consumption18,19 and exercise habits,20,21 but it is not clear whether these vary sufficiently across states to impact PD prevalence estimates. Finally, prevalence calculations can be impacted by differential mortality. Future research will seek to understand the geographic variation of PD in terms of differences in risk, mortality, and diagnostic accuracy.

The strongest risk factor for PD is age.22,23 Therefore, it is not surprising that PD prevalence estimates for individuals aged 45 and above were substantially lower than those estimated using a population sample aged 65 and older. These lower prevalence estimates reflect the uncommonness of PD diagnoses among individuals below the age of 60 and highlights the importance of presenting age-stratified data for PD burden estimates, particularly if that data includes very low-risk subpopulations.

The geographic variation in the proportion of dual-eligible individuals among PD is more challenging to explain. The most concerning potential contributing factors to high proportions of dual eligibles in a state are increased need for permanent nursing facility care due to suboptimal management of PD, or an increased incidence of outcomes that precipitate nursing home placement, such as cognitive impairment or falls with injury. Ease of obtaining Medicaid may also explain a portion of our findings; states with above-average percentages of dual eligible may have a higher relative income threshold for Medicaid eligibility, or formal/informal processes in place that facilitate Medicaid receipt. While Medicaid eligibility is administered at the state level, federal subsidies are given to states to offset the costs of the program. The amount of federal support varies from state to state, as decided by state leaders. For example, the District of Columbia, California, Arkansas, Ohio, and Connecticut, which had some of the highest proportions of dual eligible PD patients, had also opted to expand Medicaid eligibility as part of the Affordable Care Act (ACA), and had done so by 2014. ACA-supported Medicaid expansion was not designed to impact older dual eligibles; however, there may be spillover effects that result in the increased pursuit of Medicaid eligibility by PD patients in these states. Other states in the top quartile for dual eligibles—Mississippi, Louisiana, and Indiana—also have the highest proportions of individuals living at or below the poverty line.24 The interplay between the need for long-term care services, subsidies, income, and Medicaid eligibility is complex. Future studies will determine how PD patients may be uniquely impacted by state and federal level Medicare policies.

We noted in our sample that women comprised close to half of the PD population in some states. Other epidemiologic studies have shown that the incidence and prevalence of PD among women is lower than that of men.25,26 It is important to point out the distinction between disease prevalence and proportion of a disease population with a specific characteristic. When CMS datasets are used to calculate PD prevalence and incidence, the expected male:female ratio of 1.5:1 is observed.27 In this study, we focused our sex data calculations on the PD sample alone and report the proportion of Medicare beneficiaries diagnosed with PD that is female, not the prevalence of PD among female Medicare beneficiaries. Female Medicare beneficiaries outnumber male beneficiaries, and women have a greater life expectancy, both in the general population28 and among individuals with PD.29 Thus, our finding that nearly half of Medicare beneficiaries with PD are female is expected. Although women diagnosed with PD are a sizable portion of the PD population, they are highly under-represented in PD research and clinical trials. Recent data suggests that current payer models and care patterns do not meet the needs of women with PD, who have less access to specialized care and greater unreimbursed care needs.13,30 Improving PD outcomes will require increased attention to women with PD, from both research and clinical perspectives, especially given that almost half of the Medicare PD population is made up of women.

The concept of comparing Medicare utilization and cost by state was pioneered by the Dartmouth Atlas of Health Care, and their data showing significant variation has led to efforts to improve health systems across the US.31–33 In the general population, such variation is suggested to be due to regional differences in health care seeking behavior, increased need due to greater comorbid disease burden or social determinants of health, or increased availability of providers.2,34 Hospitalization for PD specialist care, such as deep brain stimulator (DBS) implantation, could contribute to our observed differences, particularly in states with multiple academic centers, however previous research has demonstrated that DBS use among Medicare beneficiaries diagnosed with PD is very low.14 In particular, our data on hospitalizations and readmissions do not follow a pattern consistent with provider availability. Excess hospitalizations and readmissions of PD patients occurred in Southern and Midwest states, which are known to have health provider shortages. Future studies will examine the nature of hospitalizations of PD patients and determine the extent to which they are PD related or avoidable (i.e., due to medication misadventure, ambulatory care sensitive condition).

Not surprisingly, we found that beneficiaries with PD have increased health care utilization and spending compared to those without PD, which is consistent with prior, smaller studies performed in the US.35,36 This was true across all sectors of care (inpatient, outpatient, skilled nursing, and ancillary services), and is in line with other data demonstrating that PD, its complications, and the shift away from comorbid disease care and prevention that occurs after a PD diagnosis drive health care spending and utilization among these individuals.12,37,38 On average, 20,142 Medicare dollars were spent per beneficiary with PD, with the lowest spent in Hawaii (12,568 USD per PD beneficiary) and the highest in Nevada (24,021 USD per PD beneficiary). Comparison of cost with other countries is difficult due to differing methodologies, inclusion of direct and indirect costs, and usually much smaller study populations, however, a comprehensive review on the subject has been done.39 PD costs in the US are most similar to Germany,40 the UK,41 and Australia42 and higher than those in Sweden, Finland, Austria, Italy, Portugal, Russia, and the Czech Republic.43,44 Hospitalizations were the main driver of cost in many of these studies.

By examining state-level variation in out-of-pocket and CMS payments, we identified regions of high and low spending, which are not consistently the regions with the highest PD prevalence. Variation in spending patterns may be due to local practice patterns,7,45 migration patterns of higher-risk individuals,2,46 or both. The proportion of state expenditures related to PD care will rise as PD prevalence increases; research to understand these variations is necessary to develop policies aimed at reducing state health care expenditures associated with undesired patient or clinical outcomes.47 In particular, economic burden data that includes the younger PD population is needed, not only to provide a complete picture of the economic burden of PD, but also because younger individuals with PD are less likely to have comorbid conditions. Thus, in this age group, medical expenditures may more directly reflect PD care costs alone.

Our study provides a comprehensive assessment of state-level variation in PD prevalence and spending patterns among the Medicare population. Nevertheless, some important limitations should be noted. We relied on administrative claims data from a single year, which may not be representative of broader secular trends in PD care. Medicare administrative claims data have been shown to be both accurate and valid48 and are commonly used in studies of spending, enabling comparison to other chronic diseases. Medicare data obtained for research purposes has been subject to a strict quality assurance process. Nevertheless, unrecognized errors in coding or reporting may occur and may be non-random. Lastly, we cannot determine the extent to which spending differences were due to hyperlocal market forces, patient factors, or physician preference. Prior studies suggest that all three factors impact the cost of care.46 More study is needed to identify the major drivers for health care spending for individuals with PD. Despite these limitations, our study provides initial evidence that there is substantial geographic variation in health service use and spending for PD. Understanding the drivers of health care costs and needs for individuals with PD is necessary to guide state- and federal-level health policies that support cost efficiency and whole person outcomes for PD patients. Our data are important from a population health and policy perspective, but can also provide meaningful information to clinicians, as knowing the burden of Parkinson’s disease in one’s state is important for physician leaders, and hospital and medical school administrators to plan for and advocate for adequate provider supplies.

Methods

This study was approved by the Institutional Review Board of the University of Pennsylvania Perelman School of Medicine. A waiver for informed consent was granted.

Data sources

The data sources for this study were the Medicare Beneficiary Summary File, which contains demographic, geographic, and detailed cost and health care utilization data on every Medicare beneficiary in the US, and Medicare Carrier Files, which contain ICD-9 and procedure codes for diagnoses made by CMS providers (e.g., physicians) in the inpatient and outpatient settings. The study population consisted of individuals aged 65 and above living in the 50 United States and the District of Columbia, who were continuously enrolled in Medicare parts A (which pays for inpatient care) and B (which pays outpatient setting care and provider services) during 2014. We excluded individuals who were enrolled in Health Maintenance Organizations or Medicare Advantage programs, as complete claims and health care use data may not be available for these individuals. We queried the Carrier Files for the ICD-9 codes “332” (Parkinson disease) and “332.0” (paralysis agitans), to identify qualifying Medicare beneficiaries with an active PD diagnosis in the year 2014. Beneficiaries were excluded if they also had diagnostic claims for secondary/drug-induced parkinsonism (“332.1”) or other degenerative disease of the basal ganglia/atypical Parkinson syndromes (“333.0”) since these diseases have a distinct pathophysiology and clinical course.

State-level PD prevalence

Residence was assigned to one of the 50 states or to the District of Columbia (hereafter referred to simply as “state(s)”) based on the beneficiary mailing address. Crude PD prevalence estimates were calculated by dividing the number of Medicare beneficiaries diagnosed with PD by the total number of Medicare beneficiaries in each state, along with 95% confidence intervals. We also calculated the proportion of PD cases in each state that was (1) aged 85+; (2) female; and (3) dual-eligible. PD is more frequently diagnosed in individuals who are identified as White and male, and PD risk increases with age. Therefore, we also calculated the age-, race-, and sex-adjusted prevalence of PD in each state, using the direct method of standardization and the total Medicare beneficiary population as the standard population.

We have recently used Medicare claims plus data from five other epidemiological studies to produce meta-estimates of the prevalence of PD in North America.49,50 These pooled data were used to produce state-level PD prevalence estimates for individuals aged 45 and above, standardized to the 2010 US census population, which we present in comparison to Medicare data-derived prevalence estimates.

For Medicare beneficiaries with and without PD, we extracted data on healthcare utilization (such as the number of emergency room visits, outpatient clinical visits, and inpatient hospitalizations), and the number and refills of covered prescriptions (available for beneficiaries receiving Medicare prescription benefits). Using reimbursement data, we calculated the mean out-of-pocket and CMS cost per individual in each state. State-level rank order lists for PD prevalence (adjusted for age, race, and sex using direct standardization), PD demographic and eligibility characteristics, PD healthcare utilization and costs were produced. Student’s t-test with equal variances and Bonferroni correction for multiple comparisons was used to compare direct costs and health service utilization for individuals with and without PD. Choropleth maps for state-level differences in PD population characteristics and cost were produced. Statistical analyses and mapping were performed using Stata/SE version 13.1 (StataCorp LP, College Station, TX, USA).

Reporting summary

Further information on experimental design is available in the Nature Research Reporting Summary linked to this article.

Code availability

Analytic code can be made available from the corresponding author upon request.

Supplementary information

Supplementary Tables 1 and 2 (303.7KB, pdf)
Reporting Summary (1.3MB, pdf)

Acknowledgements

This study was supported by the National Institutes of Health (R01NS099129) and the Parkinson's Foundation.

Author contributions

Sneha Mantri and Michelle Fullard performed data analysis, primary writing, and revision of the manuscript. James Beck provided data used in the study and critically revised the manuscript. Allison Willis provided data, performed primary statistical analysis, as well as writing and critical revision of the manuscript. Dr. Willis is the guarantor.

Data availability

The data that support the findings of this study are available through ResDAC’s CMS Data Request Center and are not publicly available. Due to CMS policy, the authors are unable to provide the data that was used in this study.

Competing interests

The authors declare no competing interests.

Footnotes

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

These authors contributed equally: Sneha Mantri, Michelle E. Fullard

Supplementary information

Supplementary information accompanies the paper on the npj Parkinson’s Disease website (10.1038/s41531-019-0074-8).

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Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Supplementary Materials

Supplementary Tables 1 and 2 (303.7KB, pdf)
Reporting Summary (1.3MB, pdf)

Data Availability Statement

The data that support the findings of this study are available through ResDAC’s CMS Data Request Center and are not publicly available. Due to CMS policy, the authors are unable to provide the data that was used in this study.

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