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eLetters: Electronic letters published:
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Diagnostic Stability: Clinical vs. Research
- Partha Pratim Das, Sandeep Grover, Assistant Professor, PGIMER, Chandigarh (20 April 2007)
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Author's reply to "Diagnostic Stability: Clinical vs. Research"
- Enrique Baca-Garcia, M. Mercedes Perez-Rodriguez, Maria A. Oquendo (8 May 2007)
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Partha Pratim Das Senior Resident, PGIMER, Chandigarh, Sandeep Grover, Assistant Professor, PGIMER, Chandigarh
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drparthapratimdas{at}yahoo.com Partha Pratim Das, et al.
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The article by Baca-Garcia et al (2007) highlights some of the important issues related to current nosological systems. However, certain issues need consideration before agreeing with the concerns raised by the authors. The authors voice their concern that with such a high degree of diagnostic instability, the validity of results of epidemiological, clinical and pharmacological research is questionable. However, it is to be remembered that in most of the research, appropriate diagnostic schedules and interviews are used for assessment of patients and studies have shown a high degree of diagnostic stability of patients assessed in such a manner (Schimmelmann et al, 2005; Tsuang et al, 1981). In their study, the authors have not discussed many factors like the level of qualification and number of years of experience in psychiatry of the evaluators, whether the patients were evaluated by the same or different assessor at each visit, the place (i.e., inpatient, outpatient, emergency) of first contact, the mean duration of contact etc, which can influence the diagnostic stability. It is also not clear, whether at each follow up proper diagnostic evaluations of subjects was done before diagnosis was recorded. Further, in the study diagnosis was entered in the register using ICD -9 codes and clinicians were using different diagnostic classification systems in coding patients, which might lead to inherent errors in conversions and reconversions. Although the authors reported that clinicians entered one or two diagnosis at the time of evaluation, in the article they have not presented any data regarding co-morbidity. Furthermore, when we compare the “diagnosis received in at least 75% of evaluations” the diagnostic stability in emergency setting was more than outpatient setting for all disorders except eating disorders. This perhaps reflects the bias of evaluators to record the previous diagnosis rather than doing a complete diagnostic evaluation in emergency. The article actually raises issues common to day to day practice and highlights the fact that the proper evaluation of patient requires use of appropriate diagnostic schedules and obtaining information from all possible sources. It will be inappropriate to conclude from the study that our diagnostic systems and all the research based on this nosological system are flawed. References: oBaca-Garcia, E., Perez-Rodriguez, M.M., Basurte-Villamor, I., et al (2007). Diagnostic stability of psychiatric disorders in clinical practice. British Journal of Psychiatry, 190, 210-216. oSchimmelmann, B.G., Conus, P., Edwards, J., et al (2005). Diagnostic stability 18 months after treatment initiation for first-episode psychosis. Journal of Clinical Psychiatry, 66, 1239-1246. oTsuang, M.T., Woolson, R.F., Crowe, R.R. (1981). Stability of Psychiatric Diagnosis: Schizophrenia and Affective Disorders. Followed up over 30 to 40 year period. Arch Gen Psychiatry, 38,535-539. |
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Enrique Baca-Garcia, Associate Professor Department of Psychiatry, Fundacion Jimenez Diaz University Hospital, Autonoma University of Madrid, M. Mercedes Perez-Rodriguez, Maria A. Oquendo
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ebacgar2{at}yahoo.es Enrique Baca-Garcia, et al.
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We thank Drs. Das and Grover for their interest. Our article reports on diagnoses of real patients in the real world. Evidently, variability ranges and the diagnostic process may be affected by factors such as psychiatrist or practice characteristics. Regarding the question of whether full assessments were performed at each visit, we believe that practitioners tend not to update diagnoses at each visit if there is no salient clinical change. We hypothesized that clinicians would be less likely to change diagnoses, biasing the data against our reported finding. Perhaps the most compelling point is that not all diagnoses were unstable. Thus, it is more likely that our findings reflect inconsistencies in our nosological system, rather than clinician or practice characteristics or setting effects. For example, some disorders may not always begin with the features required to diagnose them (e.g., mania in bipolar disorder) and therefore instability may reflect the window of time required to consolidate the diagnosis (Baca-Garcia et al., 2007). Our nosological system is in constant evolution, with major revisions each 15 years. Unfortunately, administrative procedures change more slowly than psychiatrists. Recoding from one ICD system to another may affect the validity of diagnoses, but not stability, since any error in the conversion of diagnostic codes would likely be constant, given the use of computerized algorithms. Diagnoses in pharmacological and clinical studies have good internal validity (appropriate diagnostic schedules and interviews). In general, follow-up periods are short and selection bias is likely since patients are selected from specific program or units, often based on meeting specific entry criteria. Of note, Perala et al. (2007) have recently reported that the National Hospital Discharge Register was the most reliable screen for psychotic and bipolar disorder and much better than the Composite International Diagnostic Interview (CIDI). They concluded that multiple information sources are key to accurate diagnoses. Studies like ours, where patients are followed over long periods of time and across several settings, are closer to this approach than clinical trials based on diagnostic schedules and interviews performed in a research unit over a short period of time or large cross-sectional epidemiological studies based on a single assessment. References Baca-Garcia, E., Perez-Rodriguez, M.M., Basurte-Villamor, I., et al (2007). Diagnostic stability and evolution of bipolar disorder in clinical practice: a prospective cohort study. Acta Psychiatrica Scandinavica (in press) doi:10.1111/j.1600-0447.2006.00984.x Perala, J., Suvisaari, J., Saarni, S.I., et al (2007). Lifetime prevalence of psychotic and bipolar I disorders in a general population. Archives of General Psychiatry 64, 19-28. |
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