Effects of introducing then removing cost-sharing for drugs among people with schizophrenia in Quebec: A natural experiment

Eric Latimer, Ph.D.

Canadian Health Economics Study Group

May 27 2010

Co-authors Willy Wynant, M.S.1

Adonia Naidu, M.Sc.2

Robin Clark, Ph.D.3

Ashok Malla, M.D.2,4

Erica Moodie, Ph.D.1

Robyn Tamblyn, Ph.D.1

1 Department of Epidemiology, Biostatstics and Occupational Health, McGill University

2 Douglas Mental Health University Institute3 Department of Psychiatry, McGill University4 Family Medicine and Community Health, Center for Health Policy and

Research, University of Massachusetts Medical School

Acknowledgement: Michal Abrahamowicz for contribution to original study design

Study funding Fonds de la recherche en santé du

Québec

BACKGROUND

Schizophrenia

Disabling mental illness Several subtypes Positive and negative symptoms

Usually develops around 18 for males, 25 for females (plus or minus several years)

About 1% of the population

Antipsychotics

Help control positive symptoms (psychotic episodes)

Reduce re-hospitalisations Significant side-effects Ineffective for 20 to 30% of people

with schizophrenia

Introduction of cost-sharing in August 1996 For welfare recipients and seniors

Welfare recipients: ceiling of $50 per quarter

$16.67 per month for people with mental illness

Tamblyn et al. 2001: Reduction in use of medications Increase in adverse events (deaths,

hospitalizations and nursing homes) and ER visits

Consistent with other studies Ward et al. 06 (and others):

Antipsychotics compliance: Hospitalisations Suicides, mortality

Soumerai et al. 94: Capping prescriptions for people with schizophrenia in NH: Antipsychotics Emergency psychiatric services Government costs

Selective removal of cost-sharing in October 1999 For welfare recipients classified as

disabled Includes people with schizophrenia

classified as disabled, who typically consume antipsychotics

No studies of effects of removing cost-sharing for antipsychotics identified

Qualitative interviews

Qualitative interviews In 2004-2005, 23 interviews with psychiatrists,

nurses and social workers were conducted at 8 different sites in 6 Québec cities or towns

Consumers considered, but not included for reasons of efficiency (many interviews needed to obtain representative sample)

Urban and rural, teaching and non-teaching sites included

Questions on various topics, including of relevance here: Effects of introducing, then removing cost-sharing on people with schizophrenia

Main comments from qualitative interviews

Some schizophrenia patients more closely followed than others – cost-sharing would have bigger impact on them

Removal of cost-sharing expected to have smaller impact

OBJECTIVES

Re-evaluate impact of introducing cost-sharing on use of medications, for people with schizophrenia, with larger sample

Evaluate impact of removing cost-sharing 39 months later

Data

Identification of patients Data extracted for people who had at least

one prescription of antipsychotics between Jan, 1st 1993 and Dec, 31st 2004 while on welfare status 107,005 individuals

Extracted from RAMQ: Welfare status Prescription data (DIN, duration, dose, charge,

etc.) Medical service data (type of service, Dx, etc.)

Extracted from Med-Echo: Hospitalization data (Adm. & discharge dates, Dx,

etc.)

Data cleaning

Data cleaning procedures on prescription data

Conservative methods to ensure that all the corrections are plausible. When a value seems incorrect, either:

At least 2 arguments concur to correct a value and we make this correction

Or we drop this prescription Focus on cost, quantity and duration fields

Numbers of prescriptions affected by data cleaning (based on 03 and 04 data only)

Problems of duration of prescription (number of days) = 0 & quantity of drug (i.e., total number of pills or ml) = 0 & drug cost = 0 when all not equal to zero but at least one equal to zero 442 (0.02%) prescriptions are concernedDuration of prescription > 270 days 131 (0.01%) prescriptions, only 7 could be correctedProblem with the ratio cost to quantity 91 (<0.01%) prescriptions were concerned, no one could be correctedProblem of low dose 34 (<0.01%) prescriptions were concerned, only 4 could be corrected

Patients with prescriptions that could not be corrected were eliminated from the study

Adjustment of prescription durations

Adjustments of the prescriptions: why?

If we draw successions of prescriptions for some patients we observe different patterns:

Jan, 1st Jan, 14th

Jan, 12th Jan, 25th

Jan, 1st Jan, 15th

Jan, 1st

Jan, 12th

Pills are lost

2 pills these days

1/

2/

3/

Could be

interpreted as

2 prescriptions of the same DIN:

Bases for adjustment of the prescription start dates and durations

Consulted community pharmacist near Douglas Institute

A renewal less than 20% ahead of end of previous prescription is assumed to be an early refill

But, since a pharmacist must justify to the RAMQ why s/he would have accepted to fill a renewal prescription if the patient asks for a refill more than 20% too early, we do not do this automatically in such a case.

Consecutive refills that are more than 20% too early suggest a problem – normally such events, if accepted by the pharmacist, are rare (e.g., going on vacation, lost pills)

It could be an increase in dose It could be an early renewal, concurrent with a new prescription, to

synchronize the prescriptions

Adjustment of the prescriptions: algorithm

Two prescriptions of the same DIN and the same dosage overlapped (even by more than 20%): we moved the start date of the prescription forward, to make the prescription begin when the previous one ended

Except if it was a too early renewal for the second time: we supposed that this prescription began when it was filled and that the remaining pills were lost.

Synchronized prescriptions = if there was a synchronization (two or more DINs filled on the same day) the prescription was considered as beginning when filled and the previous one was stopped (considered as if the pills were lost)

Adjustments of the prescriptions: hospitalizations

Sometimes a patient was supposed to fill a prescription during a hospitalization (even when the hospitalization was for a psychiatric reason). We supposed that all these pills were lost

When a hospitalization occurred at a time when the patient was on a prescription we supposed that all the pills from that prescription were not taken anymore and were considered as lost

Construction of the cohort

On welfare from 1993 to 2004 (ignoring interruptions < 1 month)

18+ in 1995 and alive in 2004

At least one prescription of antipsychotics every 180 days from Jan 1st 1993 to July 31st 1996, removing hospitalization days

Schizophrenia Dx either on hospitalization records OR medical records one or more times in the period 1993 – July 31st 1996

N=4,401

Proportion of days in month patient had access to antipsychotics

Proportion of days in month that antipsychotics available while in community

Adjustment for hospitalisations < 10 days in community : Proportion

undefined

First 9 months of 1993 excluded

No data from 1992 Don’t know when 1992 prescriptions end Maximum prescription duration is 9 months

High stability Moderate stability Low stability0

0.1

0.2

0.3

0.4

0.5

0.6

Subdivision of cohort into 3 sub-groups

Median coefficient of variation

Estimation strategy

Test for fixed effects or random effects

Allow for different intercepts, linear and quadratic time trends during pre-cost-sharing, cost-sharing, and post-cost-sharing periods

Results

High stability Moderate stability

Low stability0

5

10

15

20

25

30

35

40

45

Average age% Female

Age and sex by stability subgroup

High stability Moderate stability Low stability0

0.2

0.4

0.6

0.8

1

1.2

Median Antipsychotic Pos-session Ratio by Stability

Subgroup

APR

Introduction of Cost Sharing

Removal of Cost Sharing

.8.8

5.9

Ant

ipsy

chot

ic P

oses

sion

Ra

tio

0 50 100 150Month

Change in Antipsychotic Posession Ratio Across Time, All

Introduction of Cost Sharing

Removal of Cost Sharing

.6.7

.8.9

1A

ntip

sych

otic

Pos

essi

on R

atio

0 50 100 150Month

High Stability Group Moderate Stability Group

Low Stability Group

Change in Antipsychotic Posession Ratio Across Time, Stratified

Average APR in 6 months prior to cost-sharing introduction minus average APR in 6 months after cost-

sharing introduced (N=4401)

02

46

8D

ensi

ty

-1 -.5 0 .5 1drug_diff

Median difference= 0.005 Mean difference= 0.046

Average APR during 6 months after cost- sharing removed minus average APR during 6 months prior

to cost-sharing removal (N=4401)

05

10

15

Den

sity

-1 -.5 0 .5 1delta_drug

Median difference= 0 Mean difference= .0174596

Hausman test

Rejected at p<0.01 Use fixed effects

Introduction of Cost Sharing

Removal of Cost Sharing

.8.8

5.9

Ant

ipsy

chot

ic P

oses

sion

Ra

tio

0 50 100 150Month

Change in Antipsychotic Posession Ratio Across Time, All

Introduction of Cost Sharing

Removal of Cost Sharing

.6.7

.8.9

1A

ntip

sych

otic

Pos

essi

on R

atio

0 50 100 150Month

High Stability Group Moderate Stability Group

Low Stability Group

Change in Antipsychotic Posession Ratio Across Time, Stratified

Introduction of Cost SharingRemoval of Cost Sharing

.6.7

.8.9

1A

ntip

sych

otic

Pos

essi

on R

atio

0 50 100 150Month

Predicted Change in Antipsychotic Posession Ratio Across Time, All

Introduction of Cost Sharing

Removal of Cost Sharing

.6.7

.8.9

1A

ntip

sych

otic

Pos

essi

on R

atio

0 50 100 150Month

High Stability Group Moderate Stability Group

Low Stability Group

Predicted Change in Antipsychotic Posession Ratio Across Time, Stratified

Regression: High Stability Subgroup (N=1466)

Regression: Medium Stability Subgroup (N=1501)

Regression: Low Stability Subgroup (N=1434)

Sensitivity analysis

Remove values 3 months before and 3 months after August 1 1996 and October 1 1999 To mitigate any effects of stockpiling

or delaying purchasing of medications in anticipation of policy change

Results qualitatively similar

Discussion

Conclusions

High-stability group: Permanent reduction in APR, small effect of removing cost-sharing

Other groups: Long-term trends towards increased

consumption Apparently greater effect of removing

cost-sharing

Limitations

Non-experimental design: possible confounding

CV classification crude Schizophrenia Dx identification Fixed cohort – drop-outs (welfare

exit, death) ignored, possible bias

Implications

Removing cost-sharing was effective policy

Permanent effect of having introduced cost-sharing – especially for high stability group

Further evidence that cost-sharing for antipsychotics undesirable