The strength of our data is the national coverage of all inpatient treatment facilities including care in psychiatric as well as somatic clinics. In common with most developed nations, there has been a reduction in inpatient psychiatric care in Sweden over the past two decades. However, a recent study showed that while the total number of days spent in psychiatric beds in Sweden between 1994 and 2003 fell dramatically, the number of admissions scarcely changed31. A limitation of the current study is the use of unstandardized diagnoses made by different clinicians with a range of orientations. This is inherent problem with population based studies of this kind. Nevertheless, validation studies confirm a very low number of false positive diagnoses32,33. There was 94% agreement between register diagnoses of schizophrenia and research diagnoses based on semi-structured interviews and medical records33. The validity of a discharge diagnosis of bipolar disorder has not been examined, but is likely high as for schizophrenia considering a conservative and restrictive diagnostic culture for psychoses in Sweden. A small number of cases may have been treated entirely outside
