1. Factors that could modify the effects of co‐payments or cap policies.

FACTOR	CONDITION	POTENTIAL EFFECTS
Size of cap/co‐payment	Effect of the policy will be dependent on how strict the co‐payment policy is (i.e. size of co‐payment, time and volume included in cap or ceiling, period of time included in maximum co‐payment policies, etc)	If too strict: Medicine use: decrease Health: decrease Healthcare utilisation: increase Patient medicine expenditures: increase Insurer medicine expenditures: decrease Other insurer expenditures: increase If too generous: Medicine use: no change/increase Health: no change Healthcare utilisation: no change Patient medicine expenditures: no change Insurer medicine expenditures: no change/increase Other insurer expenditures: no change
Medicine groups	Suitable medicine groups should be included in the policy. Most co‐payment policies aim to reduce overuse of medicines and to control expenditures, targeting particularly “less‐essential” medicines. However, when co‐payments are applied to all prescription medicines in general, risk of discontinuation of important medicines occurs Also, consuming behaviour from patient perspective will be affected by his perception of need. Patients may be more motivated to not interrupt symptomatic treatment than asymptomatic treatment. This premise is based on the assumption that patients will be more likely to use medicines in symptomatic situations. In relation to asymptomatic situations, patients are likely to not use medicines because of changes in expenditures or health illiteracy (Ref Leibowitz 1989)	Symptomatic treatment medicines Medicine use: no change Health: no change Healthcare utilisation: no change Patient medicine expenditures: increase Insurer medicine expenditures: decrease Other insurer expenditures: no change Asymptomatic treatment medicines Medicine use: decrease Health: decrease/no change Healthcare utilisation: increase/no change Patient medicine expenditures: no change/decrease Insurer medicine expenditures: decrease Other insurer expenditures: increase
Vulnerable populations	Ensuring that all patients have access to, and can afford, important life‐sustaining medicines. Low‐income, elderly and disabled people are especially sensitive towards co‐payments, and increased medicine expenses may cause discontinuation of important medicines. Not taking this population into consideration, the policy may result in higher healthcare utilisation, deterioration of health and higher overall healthcare expenditures When experiencing chronic conditions, these vulnerable groups that are in need of multiple medicines may be particularly susceptible to co‐payment policies as they are more likely to exceed any cap levels, or to use a large number of medicines that may add up to large co‐payments	Medicine use: decrease Health: decrease Healthcare utilisation: increase Patient medicine expenditures: increase Insurer medicine expenditures: decrease Other insurer expenditures: increase
Enforcement	Adequate incentives for enforcer to comply with the policy. Co‐payments in most cases are enforced by pharmacists or by the physician	Medicine use: no change Health: no change Healthcare utilisation: no change Patient medicine expenditures: no change/increase Insurer medicine expenditures: decrease/no change Other insurer expenditures: no change
Patient level of information	Adequate follow‐up and information provided to patients. As many co‐payment policies expect patients to prioritise use of important and life‐sustaining medicines over “less essential medicines”, much responsibility is put on patients to make good choices about their own health and knowledge of pharmacotherapy. However, without enough information, patients may choose differently, for example, prioritising “less essential” medicines that are associated with more rapidly experienced discomfort if discontinued	Medicine use: no change (in important medicines) Health: increase Healthcare utilisation: no change Patient medicine expenditures: no change/decrease Insurer medicine expenditures: no change Other insurer expenditures: no change/decrease
Enforcer level of information	Adequate follow‐up and information provided to enforcer. How much information prescribers or pharmacists have about the policy concerning prescription and dispensation of medicines and how involved the patient is in the decision making are important factors Also, to what extent the enforcer is informed about the price of medicines, medicine substitution possibilities or patients’ ability to pay may influence the impact of the policy Potential consequences may be that use of medicines is unchanged, and that further economic strain is put on the patient (instead of, for example, substituting for less expensive medicines)	Medicine use: no change/increase Health: no change Healthcare utilisation: no change Patient medicine expenditures: no change/decrease Insurer medicine expenditures: decrease Other insurer expenditures: no change
Exemptions	Reasonable mechanisms for patients who need exemptions for medical reasons. However, too generous exemptions may minimise potential effects of the policy In some cases, the pharmacist or the physician has the power to exempt patients from co‐payments, but then will be liable for these expenses themselves. If such an exemption is easily attainable for the patient, little reduction in medicine use can be expected, although the policy may still save third‐party expenditures. Instead of a shift of cost from insurer to patient, a shift of cost occurs from insurer to enforcer [VL1]	If too strict: Medicine use: decrease Health: decrease Healthcare utilisation: increase Patient medicine expenditures: increase Insurer medicine expenditures: decrease Other insurer expenditures: increase If too generous: Medicine use: no change/increase Health: no change Healthcare utilisation: no change Patient medicine expenditures: no change/decrease Insurer medicine expenditures: no change/increase Other insurer expenditures: no change Reasonable: Medicine use: no change Health: no change Healthcare utilisation: no change Patient medicine expenditures: no change Insurer medicine expenditures: no change Other insurer expenditures: no change