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Table 3 Results — association between prescription drug insurance/cost-sharing and drug use, general population

From: A systematic umbrella review of the association of prescription drug insurance and cost-sharing with drug use, health services use, and health

Authors, year

Results — drug use, general population

Harten, Ballantyne, 2004 [16];

 – Canadians

Found either no change in utilization or a decrease in essential and nonessential medications following introduction of or increases in drug cost-sharing.

Magnitude: unclear.

Gibson, Ozminkowsky, Goetzel, 2005 [19];

– Demand for prescription drugs

Higher levels of drug cost-sharing resulted in reductions in prescription drug use.

Magnitude: most estimates of own-price elasticity suggested that a 10% increase in price decreased use by 1 to 4%.

– Medication adherence:

Patients facing cost-sharing were less likely to adhere to prescribed medications.

Magnitude: unclear.

– Non-preferred vs. preferred brand-name drugs:

All studies reviewed showed that increasing drug cost-sharing for non-preferred brand-name drugs decreased use of non-preferred brand-name drugs and increased use of preferred brand-name drugs.

Magnitude: unclear.

– Generic substitution:

Little evidence of generic substitution in plans introducing or increasing a generic vs brand cost-sharing differential.

Magnitude: unclear.

– Substitution of over-the-counter drugs for prescription drugs:

Limited and inconclusive findings.

Magnitude: unclear.

– Essential medications:

Higher levels of prescription drug cost-sharing were associated with a reduction in the consumption of essential medications.

Magnitude: unclear.

Briesacher, Gurwitz, Soumerai, 2007 [21];

Not having prescription drug coverage was a significant and robust risk factor for cost-related nonadherence in all reviewed studies.

Magnitude: unclear; duration of coverage and type of coverage affected the magnitude of associations.

Gemmil, Costa-Font, McGuire, 2007 [23];

Higher cost-sharing was negatively associated with the demand for prescription drugs.

Magnitude: the demand for prescription drugs was relatively inelastic. The estimated corrected own-price elasticity was − 0.21 (mean standard error 0.026); a 10% increase in cost-sharing was associated with a 2% decrease in pharmaceutical spending.

Goldman, Joyce, Zheng, 2007 [23];

– Demand for prescription drugs

Higher cost-sharing was negatively associated with the demand for prescription drugs.

Magnitude: the demand for prescription drugs was relatively inelastic. Own-price elasticities ranged from − 0.2 to − 0.6; cost-sharing increases of 10% (through either higher copayments or coinsurance) were associated with a 2 to 6% decline in prescription drug use. The magnitude of association depended on class of drug and condition of patients.

– Essential and nonessential drug use

Mixed effects of the impact of copayments on essential drug use.

Magnitude: unclear.

Gemmil, Thomson, Mossialos, 2008 [24];

– Demand for prescription drugs

Individuals who faced prescription drug charges were less likely to use prescription drugs while those with insurance coverage were more likely to use them.

Magnitude: overall, the demand for prescription drugs was almost always inelastic. Studies that used aggregate data generally found that a 10% increase in price resulted in a 0.6 to 8% decrease in use while studies that used individual- or household-level data generally found that a 10% increase in price resulted in a 0.2 to 6% decrease in use.

– Volume of drug use:

Most studies included found a negative relationship between prescription cost-sharing and levels of prescription drug use while insurance coverage had a positive effect on the volume of drug used.

Magnitude: unclear.

– Brand-name vs generic drugs:

The demand for brand-name drugs was more price-elastic than that of generic drugs.

Magnitude: The demand for brand-name and the demand for generic drugs were both relatively inelastic.

– Essential and nonessential drug use:

Most studies found that prescription drug charges lowered the use of essential and nonessential drugs, although reductions in the use of nonessential drugs were usually slightly larger.

Magnitude: unclear.

Remler, Greene, 2009 [25];

There was an inverse association between pharmaceutical cost-sharing and pharmaceutical spending/use. There was mixed evidence that pharmaceutical cost-sharing affected essential drugs differently.

Magnitude: on average, a 10% increase in pharmaceutical cost-sharing (measured as equivalent coinsurance) resulted in decreases of 2 to 6% in pharmaceutical spending/use.

Green, Maclure, et al., 2010 [26];

Restriction to reimbursement decreased drug use, either immediately after policy implemented or long-term. Impact varied by drug class and whether restrictions were implemented or relaxed.

Magnitude: unclear.

Holst, 2010 [27]

Consistent findings that increasing prescription cost-sharing reduced drug use and patient compliance to drug therapies. Effect varied depending on class of substance.

Magnitude: unclear.

Swartz, 2010 [29];

Increased cost-sharing for prescription drugs was associated with declines in use and spending on drugs. The evidence was unclear whether people responded to increased cost-sharing by switching to less expensive, close drug substitutes. With increased cost-sharing, both essential and nonessential drug use was decreased but the decrease was larger for nonessential drugs.

Magnitude: increased cost-sharing of about 10% was associated with a decline of between 1 and 6% in spending on prescription drugs.

Baicker, Goldman, 2011 [30];

Higher cost-sharing was negatively associated with the demand for prescription drugs.

Magnitude: The evidence suggested a price elasticity for drug expenditures of − 0.2 to − 0.6. The range reflected differences in responsiveness by drug class and its importance.

Eaddy, Cook, et al., 2012 [32];

Most studies found a statistically significant relationship between increased patient drug cost-sharing and decreased medication adherence. The effect depended on the population and intervention.

Magnitude: overall, a $10 increase was associated with a 3.8% decrease in adherence.

Sinnott, Buckley, et al., 2013 [36];

 – Publicly insured populations

There was a positive association between copayments and nonadherence.

Magnitude: summary odds ratio for nonadherence was 1.11 (95%CI 1.09, 1.14); publicly insured patients who were required to pay copays for their prescription medicines had 11% higher odds of reporting nonadherence relative to those who faced no copayments.

Kiil, Houlberg, 2014 [37];

Overall, pharmaceutical copayments had negative effects on the use of prescription medicine. The extent to which copayment affected the use of prescription medicine depended on the type of medicine as well as the patient population.

Magnitude: unclear.

Kesselheim, Huybrechts et al., 2015 [39];

– Prescription drug insurance coverage

Three studies examined the impact of drug insurance on patients’ use of drugs and adherence by comparing cohorts of patients with and without coverage. Two of three studies found that those with insurance used more drugs.

Magnitude: unclear.

– Extending drug insurance

Magnitude: one study examined the effects of extending drug coverage to patients on their drug use and found that the number of prescription fills increased non-significantly by 2 per patient-year.

– Drug insurance restriction

Six studies evaluated the effects of drug insurance restrictions on drug utilization and adherence. All studies found that drug insurance restrictions led to lower drug utilization and/or adherence.

Magnitude: unclear.

Luiza, Chavez et al., 2015 [40];

Raising direct patient payments for medicines was found to reduce the use of both important and unimportant drugs. The impact was sometimes uncertain and varied from small to moderate relative reductions.

Magnitude: unclear.

Aziz, Hatah, et al., 2016 [41];

Lower cost-sharing, higher prescription caps, subsidies, and insurance were associated with higher medication adherence.

Magnitude: unclear.

Gupta, McColl et al., 2018 [46];

– Canadians

Having prescription drug insurance was significantly associated with having access to prescription medication without financial barriers. High drug costs (>  5% of annual household income or > $20 a month out-of-pocket) was a major determinant of cost-related nonadherence.

Magnitude: unclear.

Mishuk, Fasina, Qian, 2019 [51];

– Individuals affected by US federal and state generic drug policies

Seven studies found that policies lowering prescription cost-sharing were associated with increased patient’s medication use and adherence, but the impact varied by therapeutic classes.

Magnitude: unclear