Negative symptoms in schizophrenia: a study in a large clinical sample of patients using a novel automated method

BMJ Open. 2015 Sep 7;5(9):e007619. doi: 10.1136/bmjopen-2015-007619.


Objectives: To identify negative symptoms in the clinical records of a large sample of patients with schizophrenia using natural language processing and assess their relationship with clinical outcomes.

Design: Observational study using an anonymised electronic health record case register.

Setting: South London and Maudsley NHS Trust (SLaM), a large provider of inpatient and community mental healthcare in the UK.

Participants: 7678 patients with schizophrenia receiving care during 2011.

Main outcome measures: Hospital admission, readmission and duration of admission.

Results: 10 different negative symptoms were ascertained with precision statistics above 0.80. 41% of patients had 2 or more negative symptoms. Negative symptoms were associated with younger age, male gender and single marital status, and with increased likelihood of hospital admission (OR 1.24, 95% CI 1.10 to 1.39), longer duration of admission (β-coefficient 20.5 days, 7.6-33.5), and increased likelihood of readmission following discharge (OR 1.58, 1.28 to 1.95).

Conclusions: Negative symptoms were common and associated with adverse clinical outcomes, consistent with evidence that these symptoms account for much of the disability associated with schizophrenia. Natural language processing provides a means of conducting research in large representative samples of patients, using data recorded during routine clinical practice.

Keywords: electronic health records; natural language processing; negative symptoms; psychosis; schizophrenia; text mining.

Publication types

  • Observational Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Electronic Data Processing
  • Electronic Health Records
  • Female
  • Hospitalization / statistics & numerical data*
  • Humans
  • Length of Stay / statistics & numerical data
  • London
  • Male
  • Middle Aged
  • Patient Readmission / statistics & numerical data
  • Prognosis
  • Schizophrenia / diagnosis*
  • Young Adult