194 Peer Review Medicaid Ad Private Isurace: Evidece Ad Implicatios How large is the substitutio of Medicaid for private isurace? The aswer depeds o how exactly the questio is posed. by David M. Cutler ad Joatha Gruber Health isurace coverage of wome ad childre i the Uited States over the past decade has bee marked by two strikig treds. The first is a dramatic icrease i coverage through Medicaid the public isurace program that covers low-icome wome ad childre, amog others. The secod is a equally dramatic declie i private coverage. Medicaid coverage of childre rose from 15 percet i 1987 to 21 percet i 1992, but private isurace coverage declied by almost the same amout (from 77 percet to 69 percet). O et, the uisurace rate was uchaged. For wome of childbearig age (ages fiftee to forty-four), Medicaid coverage rose from 8 percet to 11 percet, but the rate of private coverage fell from 76 percet to 71 percet. O et, the rate of uisurace rose by approximately two percetage poits. The similarity betwee the icrease i Medicaid coverage ad the reductio i private coverage for these two groups leads oe to ask whether these two treds are related. Oe atural likage betwee them is the substitutio hypothesis; that is, persos who are made eligible for Medicaid may drop their private isurace i favor of the public program. Sice the average privately isured family pays more tha $1,000 out of pocket for health care each year (icludig premium cotributios ad cost sharig) ad Medicaid is essetially free, this is ot a implausible hypothesis. 1 The extet of isurace substitutio caot be iferred from time-series data aloe. There was a sizable recessio i 1990 1991, ad there is always less private coverage ad more public coverage durig such a time. Also, there has bee a log-term secular declie i private isurace coverage i the Uited States, related to chages i the ature of employmet ad employers views about the beefits they eed to offer to attract workers. Determiig whether there is some substitutio of public for private isurace amog these other treds is a importat issue. Here we review our research o this questio. Methods. The major hurdle for ay attempt at measurig the degree of substitutio is figurig out how to differetiate betwee substitutio ad the other hypotheses oted above for chages i isurace coverage. There is o correct way to do this. If this were a cotrolled trial, we would radomly make some persos eligible for public isurace ad others ieligible. We the would examie how may of those eligible for public isurace moved from private to public isurace ad compare that with the chage i private isurace i the cotrol group. Of course, o experimet of this form has David Cutler is a associate professor i the Departmet of Ecoomics at Harvard Uiversity, ad a faculty research fellow at the Natioal Bureau of Ecoomic Research, i Cambridge, Massachusetts. Joatha Gruber is a associate professor i the Departmet of Ecoomics at the Massachusetts Istitute of Techology ad a faculty research fellow at the Natioal Bureau of Ecoomic Research. 1997 ThePeople-to-PeopleHealth Foudatio, Ic.
P e e r R e v i e w : M E D I C A I D E X P A N S I O N S bee coducted. However, we do have a reasoable proxy. Util the mid-1980s Medicaid eligibility for childre ad pregat wome was largely limited to those eligible for cash beefits uder Aid to Families with Depedet Childre (AFDC): very low icome families headed by sigle females. I respose to federal legislatio i the late 1980s ad early 1990s, Medicaid moved from a program restricted to the AFDC populatio to a broader program coverig childre ad pregat wome who had higher icomes. The chages were dramatic. By 1992 all wome with icomes below 133 percet of poverty were eligible for Medicaid coverage for pregacyrelated services; all childre up to age six i families with icomes up to 133 percet of poverty, ad all childre up to age ie i families with icomes up to 100 percet of poverty, were eligible for Medicaid coverage for all of their medical expeses. Also, states could expad eligibility for may of these groups up to 185 percet of poverty ad still receive federal matchig fuds. These expasios doubled Medicaid eligibility for pregat wome ad icreased eligibility for childre by early 50 percet. Importatly, these expasios were of differet magitudes i differet states. States that traditioally had higher AFDC eeds stadards expaded Medicaid eligibility much less tha did states with lower eeds stadards. This differetial creates a atural test of the substitutio hypothesis. If the hypothesis is right, the states with a greater expasio of Medicaid eligibility over the 1980s ad 1990s should have see a greater reductio i private isurace coverage tha states with a smaller expasio of Medicaid eligibility saw. If we look across states, the ay ecoomic factors that are commo to the atio as a whole will ot affect our estimates. To apply this test, we developed a idex of the geerosity of Medicaid policy i each state ad year. 2 There is tremedous variatio i this idex i differet states over time that allows us to carry out our test. I Pesylvaia, for example, Medicaid eligibility of pregat wome rose by twelve percetage poits, ad Medicaid eligibility of childre was essetially uchaged. I Texas, by cotrast, the eligibility of pregat wome rose by forty-three percetage poits, ad the eligibility of childre rose by twety-eight percetage poits. Exhibit 1 shows the relatio betwee chages i Medicaid eligibility ad Medicaid coverage for childre across states, betwee 1987 ad 1992. Not surprisigly, there is a strog positive relatio betwee eligibility ad coverage: States with a greater expasio of Medicaid eligibility had a greater icrease i Medicaid coverage tha states with a smaller expasio of Medicaid eligibility had. Exhibit 2 shows the relatio betwee Medicaid eligibility ad private isurace coverage over the same period. This shows the exact opposite relatio: States with a greater icrease i Medicaid eligibility had a greater declie i private coverage tha states with a smaller icrease i Medicaid eligibility had. This is just the type of evidece predicted by the substitutio hypothesis. We have explored this methodology more fully i aother paper, which examies crossstate differeces i Medicaid eligibility ad public ad private isurace, cotrollig for ecoomic ad demographic factors of the populatio i each state such as age, sex, race, educatio, family size, employmet, firm size, idustry, ad occupatio. 3 We also cotrol for state-specific uemploymet rates. As we emphasize i this earlier paper, isurace coverage is a family decisio, sice policies geerally are sold oly for idividuals ad families, ot separately for differet family members. As a result, whe wome ad childre are made eligible for Medicaid, it could cause ieligible persos i these families to drop private coverage, because the residual beefits of private isurace may ot be worth the premiums required. I additio, Medicaid policy may affect private isurace coverage by chagig employers behavior. Employers of low-wage workers may icrease workers cost sharig whe they kow that 195 H E A L T H A F F A I R S ~ J a u a r y / F e b r u a r y 1 9 9 7
P e e r R e v i e w E X H I B I T 1 Chage I Medicaid Eligibility Ad Medicaid Coverage Of Childre, 1987 1992 Percet chage i Medicaid coverage 20 17.5 15 12.5 10 7.5 5 2.5 0 AK NM TN AZ NH SC NC HI FL ND VT CT IN MT KS SD TX KY RI WVMO CA MN OK ID DC NE DE WY GA PA CO UT OR ME MD MI LA OH IA WI MS NJ VA NY IL MA 196 2.5 WA AR NV 5 0 5 10 15 20 25 Percet chage i Medicaid eligibility SOURCE: Curret Populatio Survey, March 1987 ad March 1992. the public sector is more geerous for uisured workers. I our methodology we cotrol for these factors by relatig family isurace coverage to family eligibility. Lookig oly at idividual coverage ad eligibility misses these importat liks. We estimate that because of the expasios 1.5 millio childre received Medicaid coverage betwee 1987 ad 1992 who would ot otherwise have doe so (Exhibit 3). However, the Medicaid expasios led to a declie i private isurace coverage of 0.6 millio childre. Sice the Curret Populatio Survey (CPS) does ot ask directly about pregacy, we examie the isurace coverage of all wome of childbearig age (ages fiftee to forty-four). We fid that chages i Medicaid ad private isurace coverage for wome of childbearig age were about equal. Fially, there was a small declie i coverage for ieligible persos as more family members became eligible for Medicaid. Not everyoe who is eligible for Medicaid erolls i the program automatically, however. The Medicaid expasios explicitly did ot give cotiuous coverage to wome but created a form of coditioal coverage, whereby wome are covered for oly some expeses. As a result, wome who are eligible for Medicaid i the evet of pregacy but who report themselves to be uisured actually have some partial (coditioal) isurace coverage. Ideed, evidece from case studies of the Medicaid expasios suggests that very few wome who were made eligible took advatage of this eligibility to fud preatal care. Rather, perhaps because of poor iformatio about eligibility, most wome were erolled i Medicaid by hospitals at the time of their delivery; i fact, may hospitals have set up special departmets, or cotracted with outside parties, explicitly to eroll eligible persos i Medicaid. 4 I the same vei, childre who are eligible for Medicaid but ot
P e e r R e v i e w : M E D I C A I D E X P A N S I O N S E X H I B I T 2 Chage I Medicaid Eligibility Ad Private Isurace Coverage, 1987 1992 Percet chage i private isurace coverage 15 12.5 10 7.5 5 AL WA MT 2.5 0 2.5 5 7.5 10 12.5 AK AR OR CO VA LA UT MD HI KY IDAZ MS NE NY WI OH IA WY PA IL DE MNOK TX VT CA MI SC ND KS NJ MA TN NM NV DC IN ME NC RI WV FL CT NH GA MO 197 15 5 0 5 10 15 20 25 Percet chage i Medicaid eligibility SOURCE: Curret Populatio Survey, March 1987 ad March 1992. erolled i the program are coditioally covered as well. If these childre get very sick, they likely will be erolled i Medicaid. We cout this coditioal coverage as a form of isurace. As a rough proxy for the value of coditioal coverage, we use the share of spedig by childre ad pregat wome that is i a hospital, sice this spedig likely will be covered by Medicaid should it be eeded. Doig this calculatio adds 0.9 millio wome ad 0.4 millio childre, or 1.3 millio (statistical) persos to the coverage rolls. Our et result is that the Medicaid expasios led to a effective total of 3.5 millio more persos with public coverage ad 1.7 millio fewer persos with private coverage. Extet Of Substitutio How large is the substitutio of Medicaid for private isurace? The aswer depeds o how exactly the questio is posed. Oe versio of the questio, which we cosidered elsewhere, is: What is the reductio i private isurace coverage as a share of the persos who erolled i Medicaid directly as a result of the expasios? 5 The aswer is foud i Exhibit 3: The declie i private isurace was roughly 50 percet (1.7 millio of 3.5 millio) of the icrease i Medicaid coverage iduced by the expasios. A secod versio of the questio, which Lisa Dubay ad Geevieve Keey pose else- H E A L T H A F F A I R S ~ J a u a r y / F e b r u a r y 1 9 9 7
P e e r R e v i e w E X H IB IT 3 Effect Of Medicaid Expasios O Isurace Coverage, 1987 1992 Chage i coverage (millios) Coverage of Medicaid Private Childre 1.5 0.6 Wome ages 15 44 0.7 0.8 Other adults 0.3 Total 2.2 1.7 a Coditioal coverage of wome 0.9 Coditioal coverage of childre 0.4 Total 3.5 1.7 b SOURCE: D. Cutler ad J. Gruber, Does Public Isurace Crowd Out Private Isurace? Quarterly Joural of Ecoomics 111, o. 2 (1996): 391 430. a Declie of 77 percet. b Declie of 49 percet. 198 where i this volume of Health Affairs, is: What is the reductio i private isurace coverage as a share of the total icrease i Medicaid coverage over this period? May more persos erolled i Medicaid tha did so just because of the expasios. Particularly below the poverty lie, much of the icrease i Medicaid coverage arose through icreased erollmet of those who were already eligible for Medicaid before the expasios. Sice may more persos erolled i Medicaid tha did so because of the expasios aloe, this estimate of substitutio will be smaller tha the first. Ideed, we estimate that the reductio i private coverage was about 22 percet of the icrease i Medicaid coverage. The third versio of the questio is: What share of the declie i overall private isurace coverage over the 1987 1992 period is a result of substitutio of Medicaid? The aswer to this questio is about 15 percet. This umber is relatively small. That is ot surprisig; private coverage chaged i may ways over this time period, ad the substitutio hypothesis captures oly a part of that chage. It is importat to reiterate the difficulty that our aalysis (ideed, ay aalysis) of this questio must address: the eed to cotrol for other factors affectig isurace coverage over this period. There is o defiitive way to do this. We thik that by lookig at differeces across states i the magitude of the eligibility expasios, we have avoided much of the issue of geeral chages i the ecoomic eviromet over time. Of course, a atural criticism of this approach is that ecoomic coditios may differ across states. I our work we cotrol for this by lookig withi states at the chage i coverage for childre of differet ages. Medicaid eligibility expaded much more for youger childre (uder age six) tha for older childre (over age twelve). I our results we fid that private coverage fell more for youger childre tha for older childre, eve whe state-specific ecoomic chages are cotrolled for. Our results are ot the oly results to fid substitutio betwee Medicaid ad private isurace. Others have foud evidece that Medicaid substitutes for private isurace. 6 The studies by Jaet Currie, ad Jaet Currie ad Joatha Gruber, which use methodologies similar to our ow, fid results that are also quite similar. Kimberly Rask ad Kevi Rask look at how differeces i Medicaid eligibility i differet areas of the coutry are related to differeces i private isurace coverage i these areas; they fid evidece that more geerous Medicaid eligibility is associated with lower private coverage. Dubay ad Keey rely o time-series comparisos betwee coverage of wome ad childre ad
P e e r R e v i e w : M E D I C A I D E X P A N S I O N S coverage of me, whom they treat as a cotrol group that captures geeral chages i the ecoomic eviromet. We fid our approach more covicig tha may of the others i the literature, particularly studies usig chages i private coverage for me as a cotrol group for wome or childre. As oted above, chages i coverage for me will be affected by the Medicaid expasios. Thus, the estimate of substitutio from such a aalysis will be too low. I additio, the impact of the 1990 1992 recessio may have bee differet for me ad wome, potetially ivalidatig the compariso. For example, there is a large amout of occupatioal segregatio across the sexes, ad the time-series factors may differ by occupatio. Fially, just as there is a declie i private coverage for me, there is also a icrease i Medicaid coverage for me. Aalyses that cosider me as a cotrol group ofte do ot et out this icrease i Medicaid coverage from their estimates. Policy Implicatios Our results fid evidece of substitutio of Medicaid for private isurace. What do these results imply for Medicaid policy? Here we address some of these issues. Should eligibility be restricted? Oe might be tempted to coclude that if Medicaid is substitutig for private isurace, Medicaid eligibility should be restricted to lower-icome groups. We believe that coclusio is ot warrated by the facts. Just kowig that people move from private isurace to Medicaid as Medicaid eligibility is broadeed is ot sufficiet to determie appropriate eligibility policy. For example, if the isurace policies of the group movig from private to public coverage were ot very geerous to begi with, Medicaid may improve access to care for these persos. I additio, persos who leave private isurace for Medicaid save moey the amout they would have spet o isurace ad out-of-pocket costs i the absece of Medicaid. This is a icome trasfer to a populatio group that has traditioally bee difficult to redistribute to i the past. Our estimates suggest that, o average, families that moved from private to public isurace received a implicit icome trasfer of $1,523, or 8 percet of family icome. 7 More fudametally, the results o substitutio tell us oly about the costs of coverage expasios, ot the beefits of those expasios. Just because a policy costs more tha we might like does ot mea it is a bad policy. Ay attempt to desig appropriate Medicaid policy must cosider the substitutio effect but must go further. Ideed, research by Currie ad Gruber shows importat gais from the Medicaid expasios i terms of improved use of prevetive care ad reduced mortality of ifats ad childre. 8 These fidigs imply that the Medicaid expasios lowered ifat mortality by 8.5 percet ad child mortality by 5.1 percet. The cost per life saved roughly $1 $1.6 millio is much lower tha that icurred by the govermet to save lives through a variety of other itervetios, eve with the substitutio effect built i. 9 Could Medicaid be better targeted? It may be possible, however, to target Medicaid to previously uisured persos more tha is ow doe. A problem all social isurace programs face is that of targetig beefits to the groups i eed. I the case of Medicaid policy, we would like to restrict coverage to persos who otherwise are uable to obtai isurace i the private market. If possible, we might wish to exclude persos from Medicaid coverage etirely who are offered but declie private coverage. 10 Such a mechaism might be hard to eforce, however. A more palatable alterative might be to require a buy-i to Medicaid at higher icome levels, or to require icreased cost sharig as icome icreases. A more radical alterative would be to elimiate the formal Medicaid program ad istead offer subsidies to idividuals or busiesses for the purchase of private isurace, as some states, such as Massachusetts, are cosiderig. Such a sys- 199 H E A L T H A F F A I R S ~ J a u a r y / F e b r u a r y 1 9 9 7
P e e r R e v i e w 200 tem would have other ecoomic effects but might help to limit substitutio. Is Medicaid eough? The fial issue we address is whether public policy should focus as heavily o Medicaid coverage as it ow does. I cosiderig the literature o Medicaid, we are struck by two facts. First, ot everyoe who is eligible for Medicaid eve amog the uisured erolls. I our earlier work, for example, we estimated that at most 60 percet of the uisured childre made eligible for Medicaid over the 1987 1992 period took coverage. 11 The secod fact is that the most substatial health risks of the uisured are geerally social, ot medical. The umber of lives lost to smokig, drikig, illegal drugs, ad violece amog the poor is likely far greater tha the umber of lives that could be saved by better medical care for that group. These observatios lead us to focus o outreach efforts for eligible persos as much as the availability of isurace. Perhaps the greatest gais i Medicaid effectiveess could come from earlier erollmet of those who are ow eligible but ot erolled i the system, so medical care ca have a more beeficial effect. Ideed, several states have adopted public relatios campaigs with themes such as Baby Your Baby (Utah) or Baby Love (North Carolia) to accompay expasios i Medicaid eligibility. I fact, some evidece shows that the North Carolia program had sigificat positive effects o the use of preatal care ad o birth outcomes. 12 I additio, we eed to shift our focus from workig toward the isurace of the poor to workig toward the health of the poor. As part of this, we may wat to reduce our emphasis o formal isurace coverage ad icrease our emphasis o prevetio of adverse social behavior. 13 This is a trade-off that could have far-reachig implicatios. NOTES 1. The authors discuss the theory of substitutio i more detail i D. Cutler ad J. Gruber, Does Public Isurace Crowd Out Private Isurace? Quarterly Joural of Ecoomics 111, o. 2 (1996): 391 430. 2. Ibid. Coverage ad eligibility are from the March Curret Populatio Survey (CPS). 3. Ibid. 4. U.S. Geeral Accoutig Office, Medicaid Expasios: Coverage Improves but State Fiscal Problems Jeopardize Cotiued Progress (Washigto: GAO, 1994). 5. Cutler ad Gruber, Does Public Isurace Crowd Out Private Isurace? 6. J. Currie, Do Childre of Immigrats Make Differetial Use of Public Health Isurace? (Mimeo, Uiversity of Califoria, Los Ageles, 1996); J. Currie ad J. Gruber, The Techology of Birth: Isurace Coverage, Medical Itervetios, ad Ifat Health (Mimeo, Natioal Bureau of Ecoomic Research, Cambridge, Massachusetts, 1996); L. Dubay ad G. Keey, Did Medicaid Expasios for Pregat Wome Crowd Out Private Coverage? Health Affairs (Jauary/February 1997): 185 193; ad K. Rask ad K. Rask, Public Health Isurace ad Moral Hazard (Mimeo, Colgate Uiversity, Hamilto, New York, 1995). 7. D. Cutler ad J. Gruber, The Effect of Expadig the Medicaid Program o Public Isurace, Private Isurace, ad Redistributio, America Ecoomic Review 86, o. 2 (1996): 368 373. 8. J. Currie ad J. Gruber, Savig Babies: The Efficacy ad Cost of Recet Chages i the Medicaid Eligibility of Pregat Wome, Joural of Political Ecoomy (forthcomig); ad J. Currie ad J. Gruber, Health Isurace Eligibility, Utilizatio of Medical Care, ad Child Health, Quarterly Joural of Ecoomics 111, o. 2 (1996): 431 466. 9. J. Gruber, Health Isurace for Poor Wome ad Childre i the U.S.: Lessos from the Past Decade, i Tax Policy ad the Ecoomy, ed. J. Poterba (Chicago: Uiversity of Chicago Press, forthcomig). 10. Ideed, this is exactly the structure of a recet subsidy program for the purchase of private isurace i Miesota: Persos must have bee uisured for eightee moths or more ad could ot work at a job that offered isurace. 11. Cutler ad Gruber, Does Public Isurace Crowd Out Private Isurace? 12. P. Buescher et al., A Evaluatio of the Impact of Materity Care Coordiatio o Medicaid Birth Outcomes i North Carolia, America Joural of Public Health 81, o. 12 (1991): 1625 1629. 13. D. Cutler, Cuttig Costs ad Improvig Health: Makig Reform Work, Health Affairs (Sprig 1995): 161 172.