Iranian Journal of Psychiatry 2015. 10(2):123-127.

Identifying Some Risk Factors of Time to Relapses in Schizophrenic Patients using Bayesian Approach with Event-Dependent Frailty Model
Maryam Rahmati, Mehdi Rahgozar, Farbod Fadaei, Enayatollah Bakhshi, Leila Cheraghi


Objectives: Schizophrenia patients often experience relapses once and even more with no limit on number of relapses. The time among relapses are rarely considered in studies. The aim of this study was to identify some risk factors of time to elapses in schizophrenic patients with recurrent events model in survival analysis.
Methods: In a retrospective longitudinal study, the medical records of 159 schizophrenic patients who referred to Razi hospital in Tehran from 2003 to 2005 were conveniently sampled, investigated and followed until the end of 2009. The time to recurrent relapses were considered in weeks. The patients with at least one relapse in this duration were included in the study. Event-dependent frailty model, using Bayesian approach, was applied to fit the data and identify the risk factors of time to relapses.
Results: In this recurrent failure time model, the effects of age of onset (95% CI = (0.058, 0.086)), gender (95% CI = (0.146, 0.686)), marital status (95% CI = (0.475, 0.965)) and family history (95% CI = (0.115, 0.543)) were significant on the hazard time to relapses. According to the credible interval of frailty variance, elapsed time to relapse is dependent on patients’ characteristics (95% CI = (0.084, 0.369)). Subsequent relapses are likely to be influenced by the occurrence of the first relapse, too (95% CI = (2.504, 3.079)), with decreasing hazard of time to relapse.
Conclusions: Subsequent relapses are likely dependent on the first and previous relapses. Age of onset, gender, marital status and family history are important risk factors influencing hazard of time to relapses. More studies are required to clear out the effect of other covariates with this model.


Schizophrenia; Relapse; Recurrent Events; Event Dependence Frailty Model; Bayesian approach

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Hassani J. [The evaluation of validity and reliabi1. Kessler RC, Bedirhan T. The WHO world Mental Health Surveys. USA: Cambridge University Press. 2008:144.

Funk M. Mental Health Policy and Service Guidance Package. 2003.

Lum AW, Kwok KW, Chong SA. Providing integrated mental health services in the Singapore primary care setting: The general practitioner psychiatric programme exprience. Ann Acad Med Singapore. 2008; 37:128-31.

Mueser KT, McGurk SR. Schizophrenia. Lancet 2004; 363: 2063-2072.

Mcgrath J, Saha S, Chant D, Welhom J. Schizophrenia: A Concise Overview of Incidence, Prevalence, and Mortality. Oxford Journals 2008; 30: 67-76.

Mohammadi MR, Bagher Yazdi SA, Naghavi HR, Pouretemad HR, Amini H, Rostami MR, Khalajabadi F, Mesgarpour B, . An epidemiological study of psychiatric disorders in Tehran province. J Andisheh Va Raftar 2003; 2: 4-13.

Mohammadi MR. An epidemiological survey of psychiatric disorders in Iran. Clinical practice and Epidemiology in Mental Health. 2005:1:16.

Aleman A KRS, Selten JP. Sex Differences in the Risk of Schizophrenia: Evidence from Meta-Analysis. ArchGenPsychiatry 2003; 60: 565-571.

Rabinowitz SZL. Häfner H. A population based elaboration of the role of age of onset on the course of schizophrenia. Schizophrenia Research 2006; 88: 96–101.

AbdelMalik PHJ, Chow EW, et al. Childhood Head Injury and Epression of Schizophrenia in Multiply Affected Families. Arch Gen Psychiatry 2003; 60: 231-236.

Schurhoff F, Golmard J, Szoke A. A mixture analysis of age at onset in schizophrenia. Schizophr Res 2004; 71: 35-41.

Kroken RA, Mellesdal LS, Wentzel-Larsen T, Jorgensen HA, Johnsen E. Time-dependent effect analysis of antipsychotic treatment in a naturalistic cohort study of patients with schizophrenia. European psychiatry 2012; 27: 489-495.

Sena E, Santos-Jesus R, Miranda-Scippa A, Quarantini L, Oliveira I. Relapse in patients with schizophrenia: a comparison between risperidone and haloperidol. Rev Bras Psiquiatr 2003; 25: 220-223.

1Chang S. Estimating Marginal Effects in Accelerated Failure Time Models for Serial Sojourn Times among Repeated Events. Lifetime Data Anal 2004; 10: 175-190.

Lim HJ LJ, Melzer-Lange M. Comparison of Methods for Analyzing Recurrent Events Data: Application to the Emergency Department Visits of Pediatric Firearm Victims. Accident Analysis and Prevention 2007; 39: 290-299.

Dagne G, Snyder J. Bayesian Analysis of Repeated Events using Event-Dependent Frailty Models: An Application To Behavioral Observation Data. Commun Stat Theory Methods 2010; 39: 293-310.

Cook Richard J, Lawless Jerald. The Statistical Analysis of Recurrent Events. M. Gail KK, J. Sarmet, A. Tsiatis, W. Wong, editor. New York: Springer; 2007; 286-300.

Twisk JWR, Smidt N, Vente WD. Applied Analysis of Recurrent Events: A Practical Overview. Epidemiol Community Health 2005; 59: 706-710.

Olesen AV, Parner ET. Correction for Selection using Frailty Models. Stat Med. 2006; 25: 1672-1684.

Wang MC, Chang SH. Nonparametric Estimation of a Recurrent Survival Function. J Am Stat Assoc 1999; 94:146-153.

Chen YQ, Wang MC. Nonparametric and Semiparametric trend analysis of Stratified Recurrent times. Biometrics 2000; 56: 789-794.

Chen YQ, Wang MC, Huang Y. Semiparametric Regression Analysis on Longitudinal Pattern of Recurrent Gap Times. Biostatistics 2004; 5: 277 –290.

Mortensen PB, Pedersen CB, Westergaard T, Wohlfahrt J, Ewald H, Mors O, Andersen PK, Melbye M. Effects of Family History and Place and Season of Birth on the Risk of Schizophrenia. N Engl J Med 1999; 340: 603-8.

Nielsen AS, Mortensen PB, O'Callaghan E, Mors O, Ewald H. Is Head Injury a Risk Factor for Schizophrenia?. Schizopher Res 2002; 55: 93-98.

Xiang YT, Wang CH, Weng YZ, Bo QJ, Chiu H. Predictors of relapse in Chinese schizophrenia patients: a prospective, multi-center study. Soc Psychiatry Psychiatr Epidemiol 2011; 46: 1325–1330.

Rahgozar M, Cheraghi L, Bakhshi E, Karimloo M, Fadaei F, Biglarian A. Application of recurrent events model in determining the risk factors of recurrence of schizophrenia. Razi journal of Medical Sciences 2012; 19: 7-11.

Olesen AV, Mortensen PB. Readmission risk in schizophrenia: selection explains previous findings of a progressive course of disorder. Psychological Medicine 2002; 32:1301-1307.

Robinson D, Woerner MG, Alvir JM, Bilder R, Geisler S, Koreen A, et al. Predictors of Relapse Following Response from a First Episode of Schizophrenia or Schizoaffective Disorder. Arch Gen Psychiatry 1999; 56: 241-247.


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