Delirium, a syndrome defined as a disturbance of consciousness, attention, cognition, and perception, has associated symptoms that may include disturbances in emotions, sleep, and psychomotor behaviour (1). The prevalence of delirium ranges from 10% to 30% in hospitalized patients who are medically ill, to as high as 51% in postoperative patients, and up to 80% in patients with terminal illness (2–5). Prodromal or subclinical symptoms may precede full-blown delirium by 1 to 3 days. Delirium symptoms may last from a few days to as long as 2 months but typically resolve in 10 to 12 days. Most patients with delirium recover fully; however, when untreated, delirium may progress to stupor, coma, or death. Delirium is less likely to resolve completely in elderly patients, with persistent cognitive deficits occurring frequently (2,3,5–9).
Delirium in the medically ill is associated with significant morbidity and mortality. Patients with delirium are at increased risk for various complications, such as pneumonia, decubitus ulcers, and postoperative complications, as well as longer hospital stays and poor hospital outcomes (10). Delirium results in increased risk for death in hospital and during the months following discharge (11). Studies suggest that up to 25% of patients with delirium die within 6 months of discharge (12).
Despite its morbidity and mortality, delirium is often misdiagnosed or is unrecognized by treating physicians. Armstrong and colleagues found that house staff misdiagnosed as many as 46% of delirium cases over a 5-year period (13).
Hospital discharge summaries serve as the main communication link between hospitalists and primary practitioners. Physician surveys yielding information on what a quality discharge summary should include report that a good discharge summary comprises the following: admission diagnosis, pertinent physical examination findings, laboratory results, procedures, complications in hospital, discharge diagnosis, discharge medications, active medical problems at discharge, and follow-up information (14,15). Delirium symptoms often persist following discharge and represent a risk factor for subsequent delirium episodes. Thus, delirium is an important event to record on discharge. Unfortunately, even when delirium is diagnosed and treated, it fails to be reported on the discharge summary (16).
This study examined potential factors that may influence the reporting of delirium as a diagnosis in general hospital discharge summaries.
All patients were seen in an inpatient setting. Referrals were received mainly from internal medicine and its subspecialties, and a small number of consultations were seen from the surgical specialties. Although consultation-liaison psychiatry diagnosed 80 patients with delirium, only 37 of these patients had been assessed using standardized delirium assessment and severity scales. Of these 37 cases, discharge summaries could be obtained for only 31. This paper focuses on the latter group, which comprised 11 men and 20 women, with a mean (SD) age of 73.34 (13.75) years.
The DRS and the DRS-R-98 rate each item on a 3-, 4-, or 5-point scale, with higher scores representing more intense delirium symptoms. In some cases, physical problems interfered with administering the DRS and the DRS-R-98 to the extent that some items could not be evaluated (for example, visiospatial ability). In these instances, prorated DRS and DRS-R-98 scores were derived using the mean response to the items completed as an estimate of the score for the items not completed. Cut-off scores for the DRS-R-98 were 15.25 (severity) and 17.75 (total) (19). The cut-off score for the DRS (severity) was 12.
Another measure used in assessing delirium severity in this study was the Clinical Global Impression (CGI) scale. This scale is a widely used single-item, 7-point rating of the severity of the patient’s illness, relative to others in the same population.
In the process of discharge summary review, 2 broad categories of discharge summaries were identified (that is, unstructured and structured). Most discharge summaries were in a narrative format without specific headings or a clear template. These were regarded as unstructured. A smaller number of discharge summaries, to varying degrees, contained headings or followed a template for describing aspects that related to the inpatient hospital stay. If headings included a preferred diagnosis or if a section of the discharge summary was specifically dedicated to discussion of diagnosis and comorbidities, these were regarded as structured discharge summaries. In this context, 22 discharge summaries were unstructured, and 9 were structured. Accordingly, in Table 1, results were reported according to this concept.
Table 1 sets out the proportion of discharge summaries containing the various indications of delirium. We examined the reporting of the diagnosis of delirium. For structured discharge summaries (n = 9), reporting delirium as a primary diagnosis or as a comorbidity ranged from 55% (using the word delirium) to 66% (using delirium or a synonym). None of the unstructured discharge summaries (n = 22) contained a specific delirium diagnosis or a synonym. Placing this in the context of the total sample (n = 31), only 16% contained a specific discharge diagnosis of delirium, and 19.4% made the discharge diagnosis of delirium or used a synonym.
Some unstructured discharge summaries referred to delirium or one of its synonyms without reporting it as an actual diagnosis. It was found that 32% referred to delirium, and 59% referred to delirium or a synonym. In these instances, delirium was not specifically identified as a discharge diagnosis but referred to as an event that occurred during hospitalization.
If any reference to delirium or to one of its synonyms is regarded as equivalent to making a discharge diagnosis of the condition, then unstructured discharge summaries (n = 22) reported the diagnosis in 59% of cases, and structured discharge summaries (n = 9) in 66% of cases, with the total sample (n = 31) of discharge summaries reporting the event in 61% of cases.
Of the discharge summaries, 48% reported that psychiatry had been consulted.
We examined the variables that correlated with whether or not delirium was referred to in the discharge summary. Of the 9 discharge summaries identified as structured, when the reason for admission was delirium (n = 5), the discharge diagnosis always included delirium. Conversely, in structured discharge summaries for which the admission was not delirium (n = 4), the discharge summary was unlikely to include delirium (1 summary in 4 included delirium).
When we examined whether delirium or a synonym was mentioned as a problem or event during the admission, 3 variables that were significantly correlated with this emerged (Table 2). These were the DRS-R-98 total score, the DRS-R-98 severity score, and the sex of the patient. Higher scores on the DRS-R-98 predicted a higher likelihood of including delirium in the discharge summary. Female sex was found to have a significant positive relation to the inclusion of delirium (or synonym) in the discharge summary. For 10 of 11 women, discharge summaries included delirium (or a synonym), whereas in men it was less likely to be included (only 9 of 20).
Table 3 presents the range of scores that were obtained from our patient sample using the various rating instruments. This table also includes the means and standard deviations of these scores and refers to maximum scores that might be obtained for each of these instruments, as well as their cut-off scores. The mean DRS score is 17.61, with quite a wide distribution. This score is comparable with the mean of 17.0 (SD 4.0) reported by Rockwood (8). The mean DRS-R-98 severity score is 16.10, also with a wide distribution. The DRS-R-98 total score of 21.24 includes an assessment of language impairment and thought processes, as well as a fluctuation of symptom severity. The mean CGI score is 4.20.
In this study, underreporting of an important medical event in the discharge summary coincides with the published literature. Such underreporting is also described for intracranial injuries, thoracic injuries, and spinal fractures (16). Generally, community physicians expect to be informed of complications that occur during treatment of their patient while in hospital (15). In the instance of delirium, prior episodes of delirium predict vulnerability to future episodes, not only making this a complication occurring during hospitalization but also identifying a risk factor that is important to convey to the treating physician. In addition, delirium does not resolve completely by the time of discharge in many patients (21). Residual symptoms and persistent cognitive impairment may require ongoing management following hospital discharge.
Our study found that most of the discharge summaries lacked much structure. Reporting the event of delirium was less likely to occur in the unstructured discharge summaries than in those with a more structured format. The unstructured format of most discharge summaries in our sample may be one factor that contributes to the low reporting.
In patients with delirium at the time of admission, discharge summary reporting was higher, compared with patients whose delirium developed during the inpatient stay (22). This finding indicates that greater emphasis is placed on delirium when the primary reason for admission is to investigate and to identify the etiology of the acute confusional state. This differs from cases in which delirium develops during the course of managing a primary physical problem, wherein a transient period of delirium may be sometimes expected (for example, in elderly patients hospitalized for treatment of community- acquired pneumonia) (4). In these instances, the occurrence of a mild, rapidly transient episode of delirium may be regarded as part and parcel of the pneumonia, not as a separate entity requiring specific reporting in a discharge summary.
The distribution of scores on all the rating instruments used contains low figures (reflecting less severe delirium) because, in many instances, the delirium that was diagnosed was resolving or being managed by the medical service prior to consulting us. The low scores most likely reflect that many patients’ delirium had improved and was no longer as severe at the time of rating.
Although the consultation-liaison psychiatry service had been asked to see all the patients in our study, the discharge summary mentions psychiatric involvement in only 48% of cases. We did not compare this with the level of reporting for other disciplines that may have been consulted during the course of the hospitalization.
The DRS is the most widely used instrument for rating delirium severity (23). As a result of research on the original instrument, however, the DRS-R-98 was developed and validated (19). The original DRS did not emerge as a significant predictor of discharge summary reporting of delirium, but this was the case with the DRS-R-98. This suggests that the improvements in the revised scale (for example, more weight for cognitive impairments) make it more sensitive to the variables that affect whether a clinician sees the delirium as significant enough to report at discharge.
Our data suggest that the severity of the delirium is a factor affecting delirium reporting in the discharge summary, with more severe deliria more likely to be reported. In addition, the sex of the patient appears to be related to reporting a delirium diagnosis in the discharge summary, with a higher rate of reporting in women with delirium, compared with reporting in men. We examined the relation between sex and delirium severity and found that DRS-R-98 scores did not differ significantly between men and women: mean (SD) for men 22.8 (6.56); mean (SD) for women 20.41 (5.97) (differences not significant, P > 0.25). The 2 groups were also equivalent in age: mean (SD) for men 77.5 years (15.27), mean (SD) for women 71.0 years (12.63), (difference no significant, t  = 0.97, P > 20). This suggests that the sex of the patient is in itself an important factor in reporting delirium, but the reason for the relation is unclear from the present data. The small sample size was a limitation.
Episodes of delirium that occur during a period of hospitalization for treatment of any medical disorder are underreported, even when specifically diagnosed. In this study, the exception to underreporting was for those cases in which delirium was diagnosed at the time of admission: reporting occurred in every instance.
The likelihood of reporting delirium in the discharge summary increases with the severity of the delirium, and in this regard, the DRS-R-98 seems a more useful assessment tool for evaluating delirium than the older DRS version.
The authors thank Dr Michael J Robinson, Assistant Professor, Division of Consultation-Liaison Psychiatry, Queen’s University, for manuscript review and helpful comments and suggestions.
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Manuscript received January 2003, revised, and accepted March 2003.
Previously presented at the 51st Annual Meeting of the Canadian Psychiatric Association; November 2, 2001; Montreal (QC).
Two posters were presented at the 16th World Congress on Psychosomatic Medicine; August 24, 2001; Gothenburg, Sweden; and at the 48th Annual Meeting of the Academy of Psychosomatic Medicine; November 15, 2001; San Antonio (TX).
1. Assistant Professor and Chair, Division of Consultation-Liaison Psychiatry, Department of Psychiatry, Queen’s University, Kingston, Ontario.
2. Assistant Professor, Division of Consultation-Liaison Psychiatry, Department of Psychiatry, Queen’s University, Kingston, Ontario.
Address for correspondence: Dr L van Zyl, Division of Consultation-Liaison Psychiatry, Connell-4, Suite 2-486, Kingston General Hospital, 76 Stuart Street, Kingston, ON K7L 2V7
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