The National Health Research Institute has a database that contains information on 200,432 NHI enrollees, about 1 percent of the population of Taiwan, who were chosen for the database at random. The database has been used for related studies (5). Enrollees were excluded from our study if they were born in another country or if they had not been alive and continuously eligible for the NHI for all of 2000. As a result of these criteria, 30,106 persons were excluded. An additional 44,180 enrollees were excluded from our study because they were younger than 18 years. The final sample consisted of 126,146 persons.
We divided the enrollees into four groups: no psychiatric disorder (119,092 enrollees, or 94 percent), a minor psychiatric disorder (5,262 enrollees, or 4 percent), a major psychiatric disorder without catastrophic illness registration (1,041 enrollees, or 1 percent), and a major psychiatric disorder with catastrophic illness registration (751 enrollees, or 1 percent). Each enrollee with a principal diagnosis of a psychiatric disorder was classified according to International Classification of Disease, 9th Revision, Clinical Modification (ICD-9-CM) diagnostic criteria (6). Minor psychiatric disorders include ICD-9-CM codes 300 through 316, excluding 303 through 305 and 312 through 315 (neurotic disorders, personality disorders, sexual deviations and disorders, physiological malfunction arising from mental factors, special symptoms or syndromes, acute reaction to stress, adjustment reaction, specific nonpsychotic mental disorders due to organic brain damage, depressive disorder not elsewhere classified, and psychic factors associated with diseases classified elsewhere) (5). Major psychiatric disorders include ICD-9-CM codes 290 through 298 (senile and presenile organic psychotic conditions, alcoholic psychoses, drug psychoses, transient organic psychotic conditions, other organic psychotic conditions, schizophrenic disorders, affective psychoses, paranoid states, and other nonorganic psychosis) (5). In Taiwan enrollees with several kinds of major psychiatric disorders, including ICD-9-CM codes 290 and 293 through 297 (senile and presenile organic psychotic conditions, transient organic psychotic conditions, other organic psychotic conditions, schizophrenic disorders, affective psychoses, and paranoid states) can apply for catastrophic illness registration (5). Enrollees with this registration do not need to pay copayments when they seek mental health care. All service claims were classified into mental health services or non-mental health services, according to the category of principal diagnosis.
NHI beneficiaries are required to pay a portion of medical costs to encourage the conscientious and efficient use of medical resources, thereby preventing waste and misuse. To ease the financial burden on the public, ceilings on copayment have been placed. If an enrollee spends fewer than 30 days in the acute ward or 180 days in the chronic ward, the ceiling on copayment is $24,000 per admission (costs are given in New Taiwan dollars). The upper ceiling of copayment for the entire calendar year is $40,000. The copayment rates for outpatient care range from $50 to $420 per visit, according to the level of service provided.
Patients with catastrophic illness registration for psychiatric disorders do not pay copayments when they seek mental health care, although they still must pay them for non-mental health services. If there was not a catastrophic illness registration system, it is possible that the copayment would be high enough to prevent many people with major psychiatric disorders from seeking care.
The mean±SE number of outpatient visits and inpatient days and the mean costs of outpatient and inpatient treatment in 2000 were calculated for each of the four groups. We used an analysis of covariance to control for age and sex (7). Use and costs of health services were adjusted by age and sex for the four groups, and the differences the groups were tested. SAS version 8.0 was used to link and analyze the data. The significance level was set at p=.01.