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Impact of different measures of comorbid disease on predicted mortality of intensive care unit patients.

BACKGROUND: Valid comparison of patient survival across ICUs requires adjustment for burden of chronic illness. The optimal measure of comorbidity in this setting remains uncertain. OBJECTIVES: To examine the impact of different measures of comorbid disease on predicted mortality for ICU patients. DESIGN: Retrospective cohort study. SUBJECTS: Seventeen thousand eight hundred ninety-three veterans from 17 geographically diverse VA Medical Centers and 43 ICUs were studied, admitted between February 1, 1996 and July 31, 1997. MEASURES: ICD-9-CM codes reflecting comorbid disease from hospital stays before and including the index hospitalization from local VA computer databases were extracted, and three measures of comorbid disease were then compared: (1) an APACHE-weighted comorbidity score using comorbid diseases used in APACHE, (2) a count of conditions described by Elixhauser, and (3) Elixhauser comorbid diseases weighted independently. Univariate analyses and multivariate logistic regression models were used to determine the contribution of each measure to in-hospital mortality predictions. RESULTS: Models using independently weighted Elixhauser comorbidities discriminated better than models using an APACHE-weighted score or a count of Elixhauser comorbidities. Twenty-three and 14 of the Elixhauser conditions were significant univariate and multivariable predictors of in-hospital mortality, respectively. In a multivariable model including all available predictors, comorbidity accounted for less (8.4%) of the model's uniquely attributable chi statistic than laboratory values (67.7%) and diagnosis (17.7%), but more than age (4.0%) and admission source (2.1%). Excluding codes from prior hospitalizations did not adversely affect model performance. CONCLUSIONS: Independently weighted comorbid conditions identified through computerized discharge abstracts can contribute significantly to ICU risk adjustment models.

APACHE↗

Relative prevalence of comorbidities and treatment contraindications in HIV-mono-infected and HIV/HCV-co-infected veterans.

OBJECTIVES: To determine the prevalence of hepatitis C virus (HCV) co-infection among HIV-infected veterans, assess the prevalence of comorbid conditions that may complicate or limit treatment options, and ascertain whether comorbid conditions were more common in co-infected veterans. DESIGN AND METHODS: We used the Veterans Administration electronic medical records system to identify all veterans receiving care for HIV during fiscal years 1997-2002. Demographic data and diagnostic codes for HIV, HCV, and comorbid conditions were extracted. The validity of using diagnostic codes was assessed by calculating the agreement between chart extraction and electronic data on a separate sample of veterans. Factor analysis was used to identify the structure underlying the intercorrelation between comorbid conditions. Logistic regression was used to compare the prevalence of comorbid conditions and factors between HIV/HCV-co-infected and HIV-mono-infected veterans, adjusting for age and race. RESULTS: We identified 25,116 HIV-infected veterans in care, of whom 4489 (18%) were HCV co-infected. A validity assessment revealed moderate agreement between chart extraction and electronic data for each of the comorbid conditions assessed. HIV/HCV-co-infected veterans were significantly more likely to have each of the comorbid conditions, and to have significantly more comorbid conditions. Factor analysis revealed three dimensions of comorbidity: mental disorders, medical disorders, and alcohol-related complications. Veterans with co-infection were significantly more likely to have mental disorders and alcohol-related complications. CONCLUSIONS: HIV/HCV-co-infected veterans had a higher prevalence of comorbid conditions that may complicate and limit treatment options for HIV and for HCV co-infection. Strategies to improve treatment options for co-infected patients with comorbidities must be developed.

Adolescent↗

Comparison of comorbidity indices for patients with head and neck cancer.

BACKGROUND: Comorbidity is an important prognostic factor for elderly patients with head and neck cancer. Investigators are faced with the dilemma of selecting the appropriate comorbidity instrument for outcomes research in cancer. The goal of this study was to compare 2 general comorbidity indices with 2 disease-specific indices. METHODS: The Surveillance, Epidemiology, and End Results (SEER)-Medicare-linked database was used to identify 15,493 patients with incident squamous cell carcinomas of the oral cavity, pharynx, and larynx first diagnosed between December 1983 and December 1994. Comorbid ailments were identified through the use of the International Classification of Diseases, 9th edition codes in the Medicare inpatient and outpatient claims for 7131 patients. The overall severity of comorbidity was classified according to 2 general comorbidity indices: the Charlson Comorbidity Index and the Klabunde Index, and 2 disease-specific indices: the Washington University Head and Neck Index and the Head and Neck Cancer Index. Overall survival was the primary end point. Cox proportional hazards analysis was used to assess the performance and discrimination of the comorbidity indices. RESULTS: For each of the 4 comorbidity indices, there was a weak trend of worse survival with higher levels of comorbidity. The 2 general indices performed as well as the 2 disease-specific indices and no instrument clearly performed better than the others. CONCLUSION: Both the general and disease-specific comorbidity indices provided important prognostic information. The disease-specific indices did not perform better than the general indices. In this claims-based analysis, there was no apparent advantage to using a disease-specific index when attempting to predict overall survival.

Aged↗

Comorbidity of irritable bowel syndrome in general practice: a striking feature with clinical implications.

BACKGROUND: Somatic comorbid symptoms might identify irritable bowel syndrome patients with different aetiologies and needs of treatment. AIMS: To measure comorbid symptoms in patients with irritable bowel syndrome in general practice, and to explore characteristics of patients with low, intermediate and high somatic comorbidity. METHODS: Prospective study of 208 of 278 consecutive patients with irritable bowel syndrome (Rome II) in nine general practices. Questionnaires assessed 22 comorbid symptoms (subjective health complaint inventory), psychosocial factors including psychological distress (Symptom Check list-10) and quality of life (Short form-12). Subjective health complaint data from 1240 adults (controls) constituted a reference material. Patients with low, intermediate and high somatic comorbidity were identified by a somatic comorbidity score (17 subjective health complaint items). Health care seeking was assessed after 6-9 months. RESULTS: Patients with irritable bowel syndrome (67% females, mean age 50, s.d. 16) reported 20 of 22 comorbid symptoms significantly more frequent than controls (odds ratios = 2-7, P < 0.001). The somatic comorbidity score correlated with psychological distress (R = 0.46, P < 0.001). Patients with high somatic comorbidity reported higher levels of mood disorder, health anxiety, neuroticism, adverse life events and reduced quality of life and increased health care seeking when compared to those with low and intermediate somatic comorbidity (P-values < 0.05). CONCLUSIONS: Our findings support the hypothesis that structured assessment of comorbid somatic symptoms might identify subgroups with different aetiology and needs of treatment.

Adult↗

Medical comorbidity in psychiatric inpatients: relation to clinical outcomes and hospital length of stay.

Medical comorbidity is common in psychiatric inpatients and may be associated with substantial impairment and mortality. Few studies have examined the relation between this comorbidity and psychiatric outcomes. A series of 950 admissions to the Johns Hopkins Hospital Phipps Psychiatric Service were rated by attending psychiatrists at admission and discharge on symptom and functional measures. A subset was also evaluated on the General Medical Health Rating, a valid and reliable measure of seriousness of medical comorbidity. Attending psychiatrists were also asked at discharge whether medical comorbidity had been a focus of care during the hospitalization; medical comorbidity had been a focus of care in about 20% of the patients. Serious active medical comorbidity was present in 15% of patients on admission and 12% at discharge. Medical comorbidity was associated with a 10%-15% increase in psychiatric symptoms and functional impairment at discharge, even after adjustment for admission clinical status. In addition, when comorbidity had been a focus of care during the hospitalization, length of stay was prolonged by 3.25 days on average. Medical comorbidity has measurable effects on the psychiatric outcomes of psychiatric inpatients and in some cases prolongs hospital stay. Psychiatrists should redouble their efforts to detect and treat this comorbidity and should consider whether special inpatient units might be needed to care for psychiatric patients with complex medical comorbidity.

Adolescent↗

Occurrence and clinical correlates of psychiatric comorbidity in patients with psychotic disorders.

BACKGROUND: The aim of this study was to explore patterns and clinical correlates of psychiatric comorbidity in patients with schizophrenia spectrum disorders and mood spectrum disorders with psychotic features. METHOD: Ninety-six consecutively hospitalized patients with current psychotic symptoms were recruited and included in this study. Index episode psychotic diagnosis and psychiatric comorbidity were assessed using the Structured Clinical Interview for DSM-III-R-Patient Version (SCID-P). Psychopathology was assessed by the SCID-P, Brief Psychiatric Rating Scale, Scale for the Assessment of Negative Symptoms, and Hopkins Symptom Checklist. Awareness of illness was assessed with the Scale to Assess Unawareness of Mental Disorders. RESULTS: The total lifetime prevalence of psychiatric comorbidity in the entire cohort was 57.3% (58.1% in schizophrenia spectrum disorders and 56.9% in mood spectrum psychoses). Overall, panic disorder (24%), obsessive-compulsive disorder (24%), social phobia (17.7%), substance abuse (11.5%), alcohol abuse (10.4%), and simple phobia (7.3%) were the most frequent comorbidities. Within the group of mood spectrum disorders, negative symptoms were found to be more frequent among patients with psychiatric comorbidity than among those without comorbidity, while such a difference was not detected within the group of schizophrenia spectrum disorders. Social phobia, substance abuse disorder, and panic disorder comorbidity showed the greatest association with psychotic features. An association between earlier age at first hospitalization and comorbidity was found only in patients with unipolar psychotic depression. Patient self-reported psychopathology was more severe in schizophrenia spectrum patients with comorbidity than in those without, while such a difference was less pronounced in mood spectrum psychoses. CONCLUSION: These findings suggest that psychiatric comorbidity is a relevant phenomenon in psychoses and is likely to negatively affect the phenomenology of psychotic illness. Further studies in larger psychotic populations are needed to gain more insight into the clinical and therapeutic implications of psychiatric comorbidity in psychoses.

Adult↗

Clinical characteristics of patients with comorbidity of migraine and epilepsy.

OBJECTIVE: Neuronal hyperexcitability might explain the comorbidity of migraine and epilepsy. Spreading depression, a postulated pathophysiological mechanism of epileptic seizures and migraine with aura, may hypothetically be the link between the disorders in these comorbid conditions. The aim of the present study was to determine whether certain clinical characteristics associated with spreading depression are overrepresented in patients with comorbidity. METHODS: In an outpatient clinic-based series, clinical characteristics of 61 patients with a comorbidity of migraine and epilepsy were compared to those of 280 patients with epilepsy alone and 248 patients with migraine alone. Patients were interviewed with a standardized questionnaire. RESULTS: The proportion of females was significantly higher in patients with comorbidity and patients with migraine as compared to patients with epilepsy (P <.001). Comparing patients with epilepsy and comorbidity, the frequency of epilepsy syndromes and seizure types was not significantly different. Comparing patients with migraine and comorbidity, migraine with aura was significantly more frequent in patients with comorbidity (P =.019). Other migraine features such as moderate to severe pain intensity, worsening of pain on activity, phonophobia, and photophobia were significantly more frequent in patients with comorbidity as compared to patients with migraine (P < or =.001). CONCLUSION: No specific epileptic characteristics could be found in patients with comorbidity. Altered cerebral excitability resulting in an increased occurrence of spreading depression may explain the differences in migraine attacks in patients with comorbidity as compared to patients with migraine alone.

Adult↗

[Relationship of psychiatric comorbidity and treatment of panic disorder and agoraphobia].

INTRODUCTION: Besides numerous studies that examined various aspects of comorbidity in patients with panic disorder and agoraphobia and numerous studies that examined efficacy of different treatment modalities in these patients, there was no study that examined relationship of overall psychiatric comorbidity and treatment of patients with panic disorder and agoraphobia. OBJECTIVE: The objective of the study was to establish the effect of psychiatric comorbidity on treatment efficiency of patients with panic disorder and agoraphobia. METHOD: The sample of the study consisted of 119 patients with primary diagnosis of panic disorder and agoraphobia. The therapy of patients was based on the use of individual integrative model of treatment, which incorporated psycho-pharmaceuticals (benzodiazepines and antidepressants) and cognitive-behavior therapy. Symptom severity was estimated by Panic and Agoraphobia Scale before and after the completion of treatment. Patients with comorbidity and patients without any comorbidity were compared by MANOVA and ANOVA with repeated measures. RESULTS: The results of the study showed that 91% of patients met diagnostic criteria of comorbid psychiatric disorder and these patients had more severe clinical picture than patients without any comorbid disorder before the treatment. The results also showed that, after the completion of treatment, there was a significant reduction of all analyzed symptoms, that the effects of treatment were significantly better in patients with psychiatric comorbidity and that comorbid psychiatric disorders had no negative effect on the main goals of the treatment. CONCLUSION: Based on these results, it may be concluded that: in patients with panic disorder and agoraphobia and comorbid psychiatric disorders, the pharmacotherapy must be based on simultaneous use of antidepressants and benzodiazepines, while standard cognitive-behavior therapy of patients with panic disorder and agoraphobia must be modified in case of the existing comorbid psychiatric disorders.

Adult↗

Association of mortality with disease severity in rheumatoid arthritis, independent of comorbidity.

OBJECTIVE: To measure the extent to which mortality in rheumatoid arthritis (RA) is associated with disease severity, independent of the presence of coexistent diseases (comorbidity). METHODS: We measured disease severity and comorbidity among RA patients attending scheduled appointments at a rheumatology clinic. We used the Duke Severity of Illness Checklist (DUSOI), a clinical judgment-based measure of the severity of disease. We disaggregated the DUSOI into an RA component (RADUSOI), which we used to measure RA disease severity, together with a physician-rated 10-point global RA severity assessment. We measured comorbidity using the non-RA component of the DUSOI (COMDUSOI) and using the Charlson Comorbidity Index. Patients were contacted periodically for up to 6 years, during which we recorded deaths. We estimated the effect of disease severity and comorbidity on mortality using Kaplan-Meier survival curves, Cox proportional hazards models, and logistic regression with receiver operating characteristics (ROC) curve analysis. RESULTS: The sample comprised 779 patients. Followup ranged from 0.1 year to 6.3 years (mean 2.52 years), for an observation period of 2,315 patient-years. Seventy-five patients died (9.6%), for a total mortality of 3.2 per 100 patient-years (95% confidence interval 2.6-4.1). Both disease severity and comorbidity displayed significant bivariate associations with mortality. In multivariate Cox models adjusted for age, sex, and disease duration, the RADUSOI and global RA severity scores were associated with mortality independent of either the COMDUSOI or Charlson Comorbidity scores. The area under the ROC curve for a logistic model on mortality increased from 0.79 with age, sex, and disease duration included, to 0.84 after adding RA severity and comorbidity (P < or = 0.005 for the increase in ROC area). CONCLUSION: RA disease severity is significantly associated with mortality regardless of the presence of comorbid disease. Combined with each patient's age, sex, and disease duration, information on RA severity and comorbidity allows an accurate prediction of mortality among patients with RA.

Adult↗

Comorbidity of body dysmorphic disorder and eating disorders: severity of psychopathology and body image disturbance.

OBJECTIVE: The current study examined comorbidity and clinical correlates of eating disorders in a large sample of individuals with body dysmorphic disorder (BDD). METHOD: Two hundred individuals with DSM-IV (4th ed. of the Diagnostic and Statistical Manual of Mental Disorders. Washington, DC: American Psychiatric Association; 1994) BDD completed reliable interviewer-administered and self-report measures, including diagnostic assessments and measures of body image, symptom severity, delusionality, psychosocial functioning, quality of life (QOL), and history of psychiatric treatment. RESULTS: A total of 32.5% of BDD subjects had a comorbid lifetime eating disorder: 9.0% had anorexia nervosa, 6.5% had bulimia nervosa, and 17.5% had an eating disorder not otherwise specified. Comparisons of subjects with a comorbid lifetime eating disorder (n = 65) and subjects without an eating disorder (n = 135) indicated that the comorbid group was more likely to be female, less likely to be African American, had more comorbidity, and had significantly greater body image disturbance and dissatisfaction. There were no significant group differences in BDD symptom severity, degree of delusionality, or suicidal ideation or attempts. Functioning and QOL were notably poor in both groups, with no significant between-group differences. However, a higher proportion of the comorbid eating disorder group had been hospitalized for psychiatric problems. This group had also received a greater number of psychotherapy sessions and psychotropic medications. CONCLUSION: Eating disorders appear relatively common in individuals with BDD. BDD subjects with a comorbid eating disorder differed on several demographic variables, had greater comorbidity and body image disturbance, and had received more mental health treatment than subjects without a comorbid eating disorder. These findings have important implications for the assessment and treatment of these comorbid body image disorders.

Adolescent↗

Alcohol and psychiatric comorbidity.

Comorbid psychiatric disorders and drug use disorders (DUDs) are common among alcoholics (Regier, Farmer, Rae, Locke, Keith, Judd, & Goodwin, 1990; Kessler, McGonagle, Zhao, Nelson, Hughes, Eshleman, Wittchen, & Kendler, 1994). These comorbid disorders often predict a shorter time to relapse of alcoholism (Greenfield, Weiss, Muenz, Vagge, Kelly, Bello, & Michael, 1998). However, despite the prevalence and the adverse effects of this comorbidity, few controlled treatment studies have been conducted involving this dual diagnosis population (Litten & Allen, 1999). To date, most of these few studies of alcoholics with comorbid disorders have been restricted to studies of alcoholics with either comorbid major depression or comorbid anxiety disorders (Litten & Allen, 1995). The results of these trials suggest efficacy for SSRI antidepressants and tricyclic antidepressants for treating alcoholics with comorbid major depression and suggest efficacy for buspirone for treating alcoholics with comorbid anxiety disorders (Mason, Kocsis, Ritvo, & Cutler, 1996; Cornelius, Salloum, Ehler, Jarrett, Cornelius, Perel, Thase, & Black, 1997; Kranzler, Burleson, Del Boca, Babor, Korner, Brown, & Bohn, 1994). However, controlled treatment studies involving alcoholics with other comorbid disorders are almost totally lacking. Consequently, to date, no empirically proven treatment exists for most of these comorbid disorders.

Alcoholism↗

Obsessive-compulsive syndromes and disorders: significance of comorbidity with bipolar and anxiety syndromes.

OBJECTIVE: To determine the prevalence and clinical characteristics of comorbid obsessive compulsive disorders and syndromes (OCD/OCS), compared with pure OCD/OCS among adults in the community. METHOD: Data were drawn from the Zurich Study, a longitudinal cohort study of 591 adults in the canton of Zurich. Comorbid OCD/OCS was compared with pure OCD/OCS groups in terms of distress, impairment, family history, suicide behavior and treatment using multivariable logistic regression analyses. RESULTS: OCD was significantly comorbid with bipolar I/II and minor bipolar disorders, anxiety states (GAD, repeated panic attacks) and social phobia, whereas there was no clear association between OCD and major depressive disorder or phobias other than social phobia. Results suggest that comorbid OCD/OCS is common among adults in the community, with the majority of those with OCD/OCS having at least one comorbid mood or anxiety disorder with a prevalence of 7.4% compared to 4.8% of remaining OCD/OCS. Comorbidity of OCD/OCS and anxiety states was more common among women (85.6 %) and comorbidity with bipolar spectrum was more common among men (69.6%). Comorbid OCD/OCS was associated with significantly higher levels of treatment seeking, impairment,distress and suicidality compared with pure OCD/OCS. Comorbidity with bipolar disorders significantly increased the risk for alcohol abuse/dependence. CONCLUSION: Comorbidity of OCD/OCS with bipolar disorder and bipolar spectrum disorders is common and very probably explains the association between OCD and depression found in other studies. The early recognition of bipolar/cyclothymic OCD/OCS may help to prevent the abuse of/dependence on alcohol.

Adult↗

Clinical and diagnostic implications of lifetime attention-deficit/hyperactivity disorder comorbidity in adults with bipolar disorder: data from the first 1000 STEP-BD participants.

BACKGROUND: Systematic studies of children and adolescents with a diagnosis of bipolar disorder show that rates of attention-deficit/hyperactivity disorder (ADHD) range from 60% to 90%, but the prevalence and implications of ADHD in adults with bipolar disorder are less clear. METHODS: The first consecutive 1000 adults with bipolar disorder enrolled in the National Institute of Mental Health's Systematic Treatment Enhancement Program for Bipolar Disorder (STEP-BD) were assessed for lifetime ADHD. The retrospective course of bipolar disorder, current mood state, and prevalence of other comorbid psychiatric diagnoses were compared for the groups with and without lifetime comorbid ADHD. RESULTS: The overall lifetime prevalence of comorbid ADHD in this large cohort of bipolar patients was 9.5% (95% confidence interval 7.6%-11.4%); 14.7% of male patients and 5.8% of female patients with bipolar disorder had lifetime ADHD. Patients with bipolar disorder and ADHD had the onset of their mood disorder approximately 5 years earlier. After adjusting for age of onset, those with ADHD comorbidity had shorter periods of wellness and were more frequently depressed. We found that patients with bipolar disorder comorbid with ADHD had a greater number of other comorbid psychiatric diagnoses compared with those without comorbid ADHD, with substantially higher rates of several anxiety disorders and alcohol and substance abuse and dependence. CONCLUSIONS: Lifetime ADHD is a frequent comorbid condition in adults with bipolar disorder, associated with a worse course of bipolar disorder and greater burden of other psychiatric comorbid conditions. Studies are needed that focus on the efficacy and safety of treating ADHD comorbid with bipolar disorder.

Adult↗

Comorbidity in patients with cancer: prevalence and severity measured by cumulative illness rating scale.

Comorbidity is defined as the presence of one or more diseases in addition to an index disease. In elderly people, the number and severity of comorbidity increase with age. We report the comorbidity data of 536 patients treated as in-patients: 231 elderly cancer patients (ECP), 172 younger cancer patients (YCP) and 133 elderly patients admitted for non-cancer reasons (EMP). Comorbidity was assessed with the cumulative illness rating scale geriatric version (CIRS-G). Data on number of affected organ systems (levels 1-4), number of affected organ systems with severe disease (levels 3-4), and sum score of levels per patient are reported. The number of comorbidities increases with age. A 76% of ECP, 51% of YCP, and 79% of EMP have severe comorbidity. Palliative treatment approach is not associated with higher levels of comorbidity in ECP. Vascular disorders were the most common comorbidity. The difficulty to rate haematological comorbidity in cancer patients is reflected. This is the first report on detailed results of assessment of comorbidity measured by CIRS-G in cancer patients. In addition, we provide a comparison to an elderly group of patients admitted for non-cancer reasons.

Age Factors↗

Chronology of comorbid and principal syndromes in first-episode psychosis.

Psychiatric comorbidity is common in psychotic disorders, but the chronology of comorbid and principal diagnoses has not been closely examined. Understanding chronology may be important for identifying risk factors, or alternatively, prodromal syndromes, for some patients with psychosis. To address this issue, we examined the rates of antecedent comorbid syndromes in patients with first-episode psychoses. Patients aged > or = 12 years presenting with psychosis were recruited from inpatient and outpatient treatment sites. Patients were excluded if they had been previously hospitalized or if symptoms resulted entirely from substance abuse or medical illness. All diagnoses were made using the Structural Clinical Interview for DSM-III-R-Patient Version (SCID-P). Comorbidity was defined as antecedent if the age of onset of the comorbidity predated the age of the onset of the psychotic disorder by more than 1 year. Seventy-one patients were recruited during a 1-year period and included 39 with bipolar disorder, 18 with schizophrenia spectrum disorders, and 14 with psychotic depression. Comorbidity was present in 69% of patients. This comorbidity was antecedent in over 80% of the patients with concurrent syndromes. Patients with psychotic depression had the highest rates of comorbidity, in particular alcohol abuse and antecedent posttraumatic stress disorder (PTSD). Comorbidity is common in first-episode psychosis and is often antecedent to the psychotic disorder. These antecedent comorbidities may represent risk factors or prodromal syndromes for the psychotic disorder.

Adolescent↗

The interaction between age and comorbidity contributes to predicting the mortality of geriatric patients in the acute-care hospital.

OBJECTIVE: To test the predictive power of comorbidity and of the interaction between age and comorbidity in geriatric patients with acute medical illness. DESIGN: Prospective observational study. SETTING: Medical and geriatric wards of an acute-care hospital. SUBJECTS: Three hundred and seventy patients over 70 years of age consecutively admitted in an 18-month period. MAIN OUTCOME MEASURE: In-hospital mortality. METHOD: On admission a multidimensional assessment was performed, and a comorbidity index and an age-comorbidity index developed on a comparable training population were calculated. The comorbidity index is based upon a scoring system that quantifies the prognostic weight of individual diseases, while the age-comorbidity index corrects the former for the age-related increase of the risk of death. The predictive power of variables univariately correlated with the outcome was tested by logistic regression. RESULTS: Death was independently predicted by clinical diagnosis of malnutrition (odds ratio = 1.87, confidence limits CL = 1.20-2.86), age-comorbidity index > 7 (odds ratio = 1.77, CL = 1.15-2.72), preadmission impairment in activities of daily living (odds ratio = 1.74, CL = 1.13-2.69), lymphocytopenia (odds ratio = 1.74, CL = 1.15-2.61). A weaker predictive model was obtained by substituting the comorbidity index for the index of age-comorbidity. Excluding comorbidity from the logistic regression greatly weakened the predictive model.

Acute Disease↗

How to adjust for comorbidity in survival studies in ESRD patients: a comparison of different indices.

BACKGROUND: Many patients with end-stage renal disease (ESRD) have additional comorbid conditions. Differences in the presence and severity of these comorbid conditions can bias comparisons between treatment groups. Adjustment for prognostic factors can statistically counterbalance these differences. For this purpose, appropriate weighting of comorbid conditions is necessary. We evaluated three existing methods to score comorbidity in patients with ESRD and compared their ability to predict survival: the Khan, Davies, and Charlson indices. In addition, these three indices were compared with a new index that explicitly incorporates the severity grading of a number of comorbid diseases. METHODS: In a large Dutch prospective multicenter study (Netherlands Co-operative Study on the Adequacy of Dialysis-2), new patients with ESRD were included. Comorbidity was assessed at the start of dialysis therapy. Patient data were randomly allocated to a modeling or testing set. The new index was developed in the modeling set. All indices were evaluated in the testing set. RESULTS: We obtained data for 1,205 patients. Of the three existing indices, the Charlson index had the best discriminating features, with a concordance c statistic of 0.71. The addition of severity grading of several comorbid conditions did not improve discrimination. After combining the comorbidity indices with age, all c statistics improved. These final values ranged from 0.72 to 0.75. CONCLUSION: We conclude that the Khan, Davies, and Charlson scores are appropriate for expressing the prognostic impact of comorbidity on mortality risk in patients with ESRD provided sufficient adjustment for age is performed. Adding the severity grading of several comorbid conditions will not lead to improved prognostic power.

Adolescent↗

Bipolar II disorder and comorbidity.

The validity and reliability of the diagnosis of bipolar II disorder has been questioned by means of comorbidity with nonaffective disorders, including substance abuse, personality disorders, and anxiety disorders. This study examined the comorbid diagnosis of a sample of bipolar II patients, comparing patients with comorbidity and those with "pure" bipolar II disorder. Forty Research Diagnostic Criteria (RDC) bipolar II patients were assessed by means of the Schedule for Affective Disorders and Schizophrenia, Lifetime Version (SADS-L) and Structured Clinical Interview for DSM-III-R axis I (SCID-II) for personality disorders. Patients fulfilling RDC criteria for any psychiatric disorder (except personality disorders) or DSM-IV criteria for any personality disorder were compared with patients without comorbidity. For practical reasons, cyclothymia was not considered as a comorbid diagnosis. Half of the sample had lifetime comorbidity with other psychiatric disorders, mainly personality disorders (33%), substance abuse or dependence (21%), and anxiety disorders (8%). However, only the rates of suicidal ideation (74% v 24%, chi square [chi2] = 9.03, P = .003) and suicide attempts (45% v 5%, chi2 = 8.53, P = .003) were significantly different between patients with and without comorbidity. In summary, although the rates of comorbidity are relatively high in bipolar II disorder, most clinical and course variables are strikingly similar in patients with and without comorbidity except for suicidal behavior, suggesting that comorbidity does not reduce the validity of the diagnosis of bipolar II disorder.

Adult↗