A systematic review of the incidence of schizophrenia. John McGrath Sukanta Saha Joy Welham David Chant.
Schizophrenia - the most common form of psychosis – is characterised by disorders of cognition (eg paranoia), affect (mood), communication (thought disorder) and perception (eg hallucinations) – leading to a loss of contact with reality along with various forms of impaired behavior.
Because schizophrenia (a) has an early onset and (b) has a relapsing or chronic course, it is a significant public health problem. It ranks in the top 10 leading causes of disability, with a burden of disease comparable to cancer and greater than heart disease.
Previously the incidence of schizophrenia has been thought to be relatively uniform across time and place. The identification of variations in the incidence of schizophrenia is important in unravelling the causes of the disorder
To systematically review studies of the incidence of schizophrenia
To examine variation in time, place and person by examining the distribution of these rates
To explore a limited number of a priori hypotheses
Males > females
Migrants > native born
Urban born > rural born
Register based studies
incidence OR prevalence)
Screen abstract and reviewed papers to cull irrelevant citations
Sex Male, Female
Age eg all ages or age 15-54
Diagnosis eg Catego S+ or Catego SPO + clinical
eg DSMIV Schizophrenia or Schizophrenia + Delusional disorder
Site overlap eg Denmark or Copenhagen
Epoch overlap eg 1990-92 or 1989-91
Rate per 100,000
Of potentially relevant papers, 74% were identified from electronic sources
There is a wealth of data available on the incidence of schizophrenia. Studies come from many countries, with many different methodological features, and conducted over several decades.
The width and skew of the rate distribution, and the significant impact of sex, urbanicity and migrant status on these distributions, indicate substantial variations in the incidence of schizophrenia.
Thus these data may provide leads for further research into risk factors