The Importance and Challenges of Longitudinal
Studies Among Patients Diagnosed With
Schizophrenia: Predicting Response to
Antipsychotic Medication Using Strata
Lina Homman, Sophie Smart, Gemma Evans, Francis O’Neill, Robin Murray, Craig Morgan, Gill Doody and James MacCabe
The self-archived postprint version of this journal article is available at Linköping University Institutional Repository (DiVA):
http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-168919
N.B.: When citing this work, cite the original publication.
Homman, L., Smart, S., Evans, G., O’Neill, F., Murray, R., Morgan, C., Doody, G., MacCabe, J., (2017), The Importance and Challenges of Longitudinal Studies Among Patients Diagnosed With
Schizophrenia: Predicting Response to Antipsychotic Medication Using Strata, Schizophrenia Bulletin, 43(suppl_1), S195-S195. https://doi.org/10.1093/schbul/sbx024.091
Original publication available at:
https://doi.org/10.1093/schbul/sbx024.091 Copyright: Oxford University Press (OUP) http://www.oxfordjournals.org/
Title: The importance and challenges of longitudinal studies among patients
diagnosed with schizophrenia; predicting response to antipsychotic medication using STRATA Authors: Homman, L.E.1 (PhD) Smart, S.² (MSc) Evans, G.³ (BSc) O’Neill, F. ¹ (FRCPsych) Murray, R.2 (FRCPsych) Morgan, C.4 (PhD) Doody, G.3 (FRCPsych) MacCabe, J.2 (PhD)
¹ Institute of Clinical Sciences, Block B. Queens University Belfast. Royal Victoria Hospital. Belfast, BT12 6BA, UK.
² Department of Psychosis Studies, Institute of Psychiatry, Psychology & Neuroscience (IoPPN), King's College London, London, UK.
³ University of Nottingham, Department of Psychiatry, Nottingham, UK.
4 Health Service and Population Research Department, Institute of Psychiatry, Psychology & Neuroscience, King's College London, London, UK.
Background
Longitudinal studies are essential for understanding the trajectory and prognosis of patients diagnosed with schizophrenia, in particular those who are
treatment-resistant as this outcome is difficult to predict. However, follow up is challenging within this patient population due to high relapse rates, difficulties re-contacting participants due to regular change of address, and patients’ symptoms leading to their refusal to take part.
Methods
We describe one of the work packages of STRATA (Schizophrenia: Treatment Resistance and Therapeutic Advances) as an example of the challenges facing follow up studies in schizophrenia research. The main aim of STRATA is to identify differences between treatment-resistant and treatment responsive patients with schizophrenia and create a method for early-identification of treatment resistant patients; thereby allowing earlier transition to more suitable treatments such as clozapine. Cohorts of patients from pre-existing studies of first episode psychosis are presently being re-contacted. Three studies across the UK (‘AESOP’, Nottingham and London samples; ‘RPGI’ and ‘NIFEPS’, Belfast samples) were included in STRATA. In total, 484 participants were eligible for re-contact; 157 participants from AESOP, 85 from the RPGI and 242 from the NIFEPS study. Participants were contacted via their clinical team, letter, or phone. Participants were invited to take part in a 40 minute interview in which demographic, substance use, medication history, and symptomology (PANSS) data was collected. Participants were also asked to provide a blood and urine sample. Ethical permission was obtained to
contact participants using information collected at previous visits and to obtain up to date contact addresses.
Results
Out of the 484 participants who were re-contacted, 13 were deceased, 9 were excluded, 23 requested information after the first contact but then ceased to respond, 47 declined to participate, and addresses were not identified for 63
participants. 34 consented and completed all the assessments. The remaining 295 participants have yet to respond.
Clozapine had been prescribed to 8.82% of completed participants and 47.06% have been prescribed 3 or more antipsychotics.
Conclusions
The present study confirms the difficulties in longitudinal studies of patients diagnosed with schizophrenia. More research is needed in order to identify the attitudes and practices which keep patients from participating in research. Additionally, in the general population, it is estimated that about two-third of
individuals diagnosed with schizophrenia are treatment-resistant. We can therefore conclude that treatment-resistance is somewhat over-represented in the present sample.
STRATA is supported by grant MR/L011794/1 from the Medical Research Council (MRC).
