MediShield
P.S. Both Health Savings Account (HSA) in the U.S. and MediShield in Singapore are similar health insurance plans used in financing of catastrophic care services such as hospitalization and physician services.
Medishield is a high-deductible catastrophic insurance plan meant to cover individuals for catastrophic services such as hospitalizations and physician services. It is financed based on risk-pooling principles for lower income Singaporeans. With high deductibles and no coverage for preventive care, psychiatric treatment, mental health, Medishield protects itself from liability by operating on insurance underwriting principles, aka experience rating. Essentially, if a patient has been receiving treatment before joining Medishield, Medishield policy can exclude that illness.
Medic-tionary for deductible: The initial costs not covered by insurance policies. For example, if deductible for a policy is $2000, any single/bundled procedure costing less than $2k will NOT be eligible for reimbursement. You are responsible for paying that out of your pocket.
Premiums are automatically deducted from another savings account, Medisave (more another time), and all enrollees in Medisave are automatically enrolled in Medishield. There is a pass option for individuals to opt out. Medishield, however, only covers up to 80 years old, and thus cannot be considered as a supposed safety net for elderly people. Lifetime maximum claims also exist.
In 2005, Medishield was reformed after being in operational deficit. 1) Caps on each treatment reimbursement were raised. For instance, Intensive Care Unit reimbursement was increased from $300 per diem to $500 per diem. Lifetime maximum claims were upped to $200k from $120k. 2) Raised Deductibles and 3) Raised premiums. Risk-pooling is maximized in Medishield with experience rating and automatic enrollment.

http://www.cpf.gov.sg/cpf_info/publication/REFORMMEDISHIELD.asp
* For members who join MediShield before age 60, there is a 10% premium discount for every ten years of coverage.
In a way, this model cleverly makes use of citizen's reluctance to make extra effort to opt out. Anyway, if one doesn't see cash moving outright from our pockets, but instead from Medisave accounts, then the Why-Not? attitude is prevalent. Furthermore, the premiums are so low, an average of $2.50 per month for those below 30 years of age, that you won't even notice the money missing from your Medisave account!
Point being: Know the benefits coverage you are entitled to under MediShield and buy private insurance policies that complement, and not overlap, those existing benefits.