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(Stroke. 1999;30:744-748.)
© 1999 American Heart Association, Inc.
Original Contributions |
From the Stroke Unit, Department of Neurology (G.M., G.J.H.), and Department of Radiology (D.C.), Royal Perth Hospital, and University of Western Australia (G.J.H.), Perth, Australia.
Correspondence to Dr Graeme J. Hankey, Royal Perth Hospital, Wellington St, Perth, Australia 6001. E-mail gjhankey{at}cyllene.uwa.edu.au
| Abstract |
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MethodsWe prospectively assembled an inception cohort of 128 hospital-referred patients with acute first stroke. We assessed swallowing function clinically and videofluoroscopically, within a median of 3 and 10 days, respectively, of stroke onset, using standardized methods and diagnostic criteria. All patients were followed up prospectively for 6 months for the occurrence of death, recurrent stroke, chest infection, recovery of swallowing function, and return to normal diet.
ResultsAt presentation, a swallowing abnormality was detected clinically in 65 patients (51%; 95% CI, 42% to 60%) and videofluoroscopically in 82 patients (64%; 95% CI, 55% to 72%). During the subsequent 6 months, 26 patients (20%; 95% CI, 14% to 28%) suffered a chest infection. At 6 months after stroke, 97 of the 112 survivors (87%; 95% CI, 79% to 92%) had returned to their prestroke diet. Clinical evidence of a swallowing abnormality was present in 56 patients (50%; 95% CI, 40% to 60%). Videofluoroscopy was performed at 6 months in 67 patients who had a swallowing abnormality at baseline; it showed penetration of the false cords in 34 patients and aspiration in another 17. The single independent baseline predictor of chest infection during the 6-month follow-up period was a delayed or absent swallowing reflex (detected by videofluoroscopy). The single independent predictor of failure to return to normal diet was delayed oral transit (detected by videofluoroscopy). Independent predictors of the combined outcome event of swallowing impairment, chest infection, or aspiration at 6 months were videofluoroscopic evidence of delayed oral transit and penetration of contrast into the laryngeal vestibule, age >70 years, and male sex.
ConclusionsSwallowing function should be assessed in all acute stroke patients because swallowing dysfunction is common, it persists in many patients, and complications frequently arise. The assessment of swallowing function should be both clinical and videofluoroscopic. The clinical and videofluoroscopic features at presentation that are important predictors of subsequent swallowing abnormalities and complications are videofluoroscopic evidence of delayed oral transit, a delayed or absent swallow reflex, and penetration. These findings require validation in other studies.
Key Words: aspiration dysphagia prognosis stroke outcome
| Introduction |
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The few studies that have assessed the natural history of swallowing function after acute stroke suggest that swallowing abnormalities recover quickly, but these studies have relied on bedside clinical examination to diagnose dysphagia and have only assessed swallowing function for short periods, such as 2 weeks, after stroke.1 5 There has been only 1 prospective study of the natural history of dysphagia after acute stroke in which swallowing function was assessed clinically and videofluoroscopically and patients were followed up for persistent swallowing difficulties for up to 6 months.10 11 However, other important outcomes, such as chest infection, were not recorded beyond 7 days after stroke, and videofluoroscopy was not repeated beyond 1 month after stroke.
We have undertaken a slightly larger prospective study of the prognosis over the first 6 months after acute stroke of swallowing function and important complications of swallowing dysfunction, such as chest infection. We have also attempted to identify the important independent clinical and videofluoroscopic prognostic factors at baseline that are associated with an increased risk of swallowing dysfunction and complications. The latter findings may serve to simplify the diagnostic assessment of swallowing function (by distinguishing relevant and irrelevant clinical and videofluoroscopic findings) and thereby may enable patients at risk to be accurately identified at presentation.
| Subjects and Methods |
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All patients were assessed neurologically by the study neurologist to establish the diagnosis of stroke (according to the standardized criteria of the World Health Organization13 ), the clinical syndrome, the pathological and etiologic subtype of stroke, and the functional effects of the stroke, as measured by the Oxford Handicap Scale and Barthel Index.
Swallowing function was assessed clinically, at the bedside, by 2 study
speech pathologists and videofluoroscopically by the study radiologist
and 1 of the study speech pathologists, using standardized methods and
diagnostic criteria (Appendix
).
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The clinical and videofluoroscopic assessment and diagnostic criteria for the presence and severity of a swallowing disorder and aspiration were developed by us and influenced by the work of Ott and Pikna,14 Linden and Siebens,15 and Logemann.16 Briefly, the clinical assessment of swallowing function was conducted by 2 speech pathologists independent of each other and blinded to the videofluoroscopic and CT brain scan findings. It comprised a history from the patient and/or relatives of swallowing ability and function before and after the stroke; an oral motor-sensory examination assessing the components of swallowing, voice, speech, and language function; and observation of the patient swallowing saliva initially (dry swallow) and subsequently after 5 mL of water, 20 mL of water, and a thickened fluid (if appropriate). The videofluoroscopic assessment was conducted by the study radiologist, who was blinded to the results of the clinical assessment and CT brain scan findings.
Patients were followed up prospectively over the first 6 months after stroke, during which time the occurrence of death, recurrent stroke, and chest infection was recorded. Recurrent stroke was defined as (1) the sudden onset of a new focal neurological deficit with no apparent cause other than that of vascular origin (ie, the deficit could not be ascribed to an intercurrent acute illness, epileptic seizure, or toxic effect) or (2) clinical evidence of the sudden onset of an exacerbation of a previous focal neurological deficit with no apparent cause other than that of vascular origin.13
Chest infection was diagnosed by the attending clinician and based on
the presence of
3 of the following variables: fever (>38°C),
productive cough with purulent sputum, abnormal respiratory
examination (tachypnea [>22/min], tachycardia,
inspiratory crackles, bronchial breathing), abnormal chest radiograph,
arterial hypoxemia (PO2
<70 mm Hg), and isolation of a relevant pathogen (positive gram
stain and culture).
At 6 months after stroke, the 112 stroke survivors were assessed clinically by the study speech pathologist. This included a detailed dietary history, with the speech pathologist recording whether the diet was different from the usual prestroke diet. The subgroup of 67 patients who had videofluoroscopic evidence of a swallowing abnormality on the initial assessment underwent a repeated videofluoroscopic assessment of swallowing function by the same assessors who conducted the initial assessment. Any swallowing abnormality (clinical or videofluoroscopic) and aspiration (videofluoroscopic) were defined according to standardized criteria.
Statistical Methods
Crude associations between the occurrence of categorical outcome
events (chest infection, dietary change, swallowing abnormality, and
aspiration) and each of the categorical baseline variables were
assessed by preliminary cross-tabulations with the
2 test or Fisher's exact test. Reverse
stepwise multiple logistic regression techniques were used to identify
important independent predictors of dietary change, swallowing
abnormality, aspiration, and chest infection at 6 months. Time to first
chest infection was analyzed with the Kaplan-Meier product
limit technique. Stepwise Cox proportional hazards multiple regression
analysis was performed to identify significant prognostic
factors for the outcome event "chest infection during the first 6
months after stroke" and to measure the relative impact of changes in
each factor on the hazard.
| Results |
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Swallowing Problems at Onset
Table 1
shows the baseline
demographic, clinical, and videofluoroscopic features of the 128 acute
stroke patients. Clinical bedside examination identified a swallowing
disorder (dysphagia) in 65 patients (51%; 95% CI, 42% to
60%) and aspiration in 64 patients (50%; 95% CI, 41% to
59%). Videofluoroscopy identified a swallowing disorder in 82
patients (64%; 95% CI, 55% to 72%) and aspiration in 28 patients
(22%; 95% CI, 15% to 30%).
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Outcome Measures
During 6 months of follow-up after stroke, 5 patients died (all
had initial videofluoroscopic evidence of swallowing
dysfunction), 12 (9%) had a recurrent stroke, and 26 (20%) had a
chest infection (24 had initial videofluoroscopic evidence of
dysphagia). The rate of chest infection was greatest in the first month
after stroke (12%; 95% CI, 7% to 18%), but chest infection occurred
throughout the follow-up period (Figure
)
and accounted for 4 of the 5 deaths in the cohort. Recurrent chest
infection occurred in 8 patients (6%; 95% CI, 2% to 12%). Cox
proportional hazards multiple regression analysis identified
delayed or absent swallowing reflex (detected by videofluoroscopy) as
the single independent predictor of chest infection during the 6-month
period (hazard ratio, 9.8; 95% CI, 2.9 to 33).
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At 6 months, the 112 survivors (88%; 95% CI, 80% to 93%) were reassessed clinically, and 11 patients (10%) were lost to follow-up. Ninety-seven of the 112 survivors (87%; 95% CI, 79% to 92%) had returned to their prestroke diet, and 15 (13%; 95% CI, 8% to 21%) had not.
Clinical evidence of a persistent swallowing abnormality was diagnosed in 56 patients (50%; 95% CI, 40% to 60%). Videofluoroscopy was performed in 67 of the 82 patients who had initial videofluoroscopic evidence of a swallowing abnormality. Despite the fact the 97 patients (87%) had returned to their prestroke diet, videofluoroscopy showed persistent swallowing abnormalities in 54 of the 67 patients studied; contrast penetrated the false cords in 34 (63%; 95% CI, 49% to 76%) and the true cords (aspiration) in another 17 (31%; 95% CI, 19% to 46%).
Multiple logistic regression analysis (Table 2
) identified the single independent
baseline predictor of chest infection at 6 months as videofluoroscopic
evidence of a delayed or absent swallowing reflex. The single
independent baseline predictor of a failure to achieve the patient's
prestroke diet at 6 months after stroke was videofluoroscopic evidence
of delayed oral transit. The independent predictors at baseline of the
combined outcome event "swallowing impairment, chest infection, or
aspiration at 6 months" were age >70 years, male sex,
videofluoroscopic evidence of delayed oral transit, and penetration
(Table 2
).
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| Discussion |
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The only comparable cohort study10 11 was also
hospital referred, but the patients were older (median age, 79 years)
than those in our cohort (median age, 71 years). Their patients were
assessed clinically within a median time of 14 hours (range, 0.5 to 50
hours) and videofluoroscopically within a median time of 1 day (range,
0 to 5 days) of stroke onset. Despite these differences and minor
differences in diagnostic criteria, the baseline results of
our study are remarkably similar. At presentation (within a
median of 1 to 3 days after stroke onset), both studies reported
clinical evidence of swallowing dysfunction in 51% of patients and
videofluoroscopic evidence of aspiration in 22% of patients. Chest
infection was only sought during the first 7 days after stroke by
Smithard et al but was nevertheless diagnosed in 25% of patients (33%
with clinical evidence of an unsafe swallow and 16% with a safe
swallow).10 We followed 112 patients for up to 6 months
after stroke and recorded chest infection during that period in
20% (n=26) of patients, of whom 9% (n=10) developed a chest infection
in the first 7 days after stroke (Figure
). The lower early rate of
chest infection in our study may be due to any or all of a number of
factors such as chance, diagnostic criteria, and treatment
strategies. However, we did find that chest infection occurred most
commonly in the first month after stroke.
Follow-up videofluoroscopy, performed at 1 month after stroke by Smithard et al,11 revealed that 12 of the 81 patients (15%) were aspirating, and 40 (49%) demonstrated supraglottic penetration. We performed follow-up videofluoroscopy at 6 months after stroke in the 67 patients who had evidence of a swallowing abnormality on the initial videofluoroscopy and found that 17 of the 67 patients (25%) were aspirating. Both studies reveal a disturbingly high prevalence of unequivocal aspiration at different times after stroke, particularly in view of the selection bias in both studies (for example, patients in our study who did not consent to an additional videofluoroscopy or who had a normal initial videofluoroscopy investigation did not undergo a repeated videofluoroscopy at 6 months).
At 6 months after stroke, we found clinical evidence of a swallowing abnormality in 50% of the 112 survivors, which contrasts with the lower prevalence of 11% among the 73 patients assessed by Smithard et al11 at 6 months. It is unlikelythat the differences reflect differences in diagnostic criteria between the studies, because the assessments at 6 months in each study were made by the same personnel using the same criteria as the baseline assessments, which revealed identical results (a 51% prevalence of swallowing abnormality). Although our estimate of swallowing dysfunction at 6 months appears unexpectedly high, it is noteworthy that 15 patients were still unable to return to their prestroke diet of their own volition, and we found unequivocal videofluoroscopic evidence of contrast penetrating the false cords in 34 patients and the true cords (aspiration) in 17 patients among the 67 patients who underwent videofluoroscopic examination at 6 months. We were unable to determine the relative proportion of swallowing abnormalities that were persistent and new. Recurrent stroke during the 6-month follow-up period may have been a relevant etiologic factor in the development of new swallowing abnormalities in up to 10 patients (it was a significant independent predictor of aspiration at 6 months), but it was not an important independent predictor of residual swallowing abnormality in the multiple regression analysis.
The statistical models derived from our data suggest that older patients (>70 years) with disabling stroke (Barthel index <60/100) may be at increased risk of subsequent swallowing complications and that videofluoroscopic evidence of a delayed or absent swallow reflex, delayed oral transit, and penetration are even stronger markers of risk. Although these models are based on small numbers of patients and are therefore unstable, they are the first attempt to identify important clinical and videofluoroscopic factors at presentation that are independently associated with important clinical outcomes. These and future efforts at modeling should help clinicians not only to identify patients at risk of complications but also to identify which components of our assessment tools are important to elicit and act on.
If these results can be validated externally in other cohorts, they would suggest that swallowing function should be assessed in all acute stroke patients (because swallowing dysfunction and its complications are common) and that the assessment of swallowing function should be both clinical and videofluoroscopic, because videofluoroscopic evidence of a delayed or absent swallow reflex, delayed oral transit, and penetration may be even more predictive of complications of swallowing dysfunction than other important clinical features, such as the age of the patient, the stroke syndrome, and its severity.
| Acknowledgments |
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Received November 16, 1998; revision received January 4, 1999; accepted January 4, 1999.
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