Keywords:
Stroke - Early Diagnosis - Emergency Medical Service - Sensitivity and Specificity
Palavras-chave:
Acidente Vascular Cerebral - Diagnóstico Precoce - Serviços Médicos de Emergência
- Sensibilidade e Especificidade
INTRODUCTION
Among chronic, non-communicable diseases, stroke is one of the main causes of death
and neurological disability worldwide. Stroke can occur through two mechanisms: occlusion,
leading to ischemic stroke; or transient ischemic attack and rupture of vascular blood
vessel(s), leading to hemorrhagic stroke[1],[2].
Stroke is a disease heavily influenced by socioeconomic factors, reflected in the
fact that the highest incidence rates are in underdeveloped and developing countries.
In Brazil, stroke is one of the main causes of mortality; however, paradoxically,
it is one of the most neglected diseases. Data released by the Brazilian Ministry
of Health demonstrated a mortality rate of 56.58/100,000 inhabitants in 2017, and
stroke ranked second among the most prevalent causes of death in the country[1],[3],[4].
Ischemic stroke is the most common type of stroke in the population. In such cases,
one of the most effective treatments is thrombolytic therapy using intravenous recombinant
tissue plasminogen activator, which should be administered within 4.5 h of the onset
of symptoms. This treatment yields excellent results and has reduced the number of
deaths and disability. However, the proportion of patients who arrive at a hospital
in a timely manner and receive treatment remains low (approximately 1 to 8%)[5],[6],[7]. Another evolving treatment that is gaining supportive evidence for its effectiveness
is mechanical thrombectomy, which can be performed 6 to 24 h after the onset of symptoms.
It involves physical removal of the thrombus using an endovascular device to restore
cerebral blood flow. It is a treatment that reduces mortality and disability among
stroke patients. Regardless of the type of treatment administered, studies have associated
success of treatment with patients’ early arrival at the emergency room, soon after
the onset of symptoms[8],[9].
In this scenario, prehospital care has become an important factor in treating stroke.
This has been associated with an increased rate of patients who arrive at a hospital
early. One of its highlights is the readiness of teams who have been trained to recognize
early symptoms of stroke and appropriately refer patients to hospitals with specialized
personnel and facilities, thus optimizing treatment. In regions where there are well-structured
primary healthcare services with priority in referring suspected cases to a specialized
hospital, thrombolytic therapy rates can reach 24%[7],[10].
Thus, to be successful in this process, it is important to qualify prehospital teams,
especially in relation to early identification of the disease. The American Heart
Association and European Stroke Organisation recommend continuing education programs
for these teams and use of internationally standardized instruments to assist healthcare
professionals in accurately recognizing stroke early[11],[12].
Worldwide, there are several such standardized instruments[13]. In Brazil, the Cincinnati Prehospital Stroke Scale (CPSS) is in widespread use
among emergency sectors. This scale assesses three changes: facial paresis, and motor
and speech changes. It demonstrates sensitivity between 79 and 95%, and specificity
between 24 and 56%. However, these figures come from studies conducted in other countries[13],[14],[15]. It is a simple instrument, very similar to the FAST scale (i.e., Face, Arm, Speech
and Time), which is also used internationally and has been associated with increased
treatment rates[11],[16].
To our knowledge, however, no studies have assessed the applicability of CPSS to the
Brazilian population. Thus, there is a need for a systematic process of translation
and cultural adaptation of this scale, along with statistical analysis on its application.
Accordingly, the objective of the present study was to translate the CPSS into Brazilian
Portuguese, and then to cross-culturally adapt and validate it using a representative
sample of the Brazilian population.
METHODS
In this prospective study, the CPSS instrument was translated, adapted and validated.
The study was conducted in a city located in the interior of the state of São Paulo,
Brazil, where there are integrated prehospital care services and a stroke center.
Both of these are certified by the Ministry of Health as part of the national urgency
and emergency policy. The prehospital service is named “SAMU 192” and teams are divided
into basic life support teams (nursing technicians and drivers) and advanced life
support teams (physicians, nurses and drivers)[17].
This study was performed in two phases. The first consisted of a systematic process
of translation and cross-cultural adaptation of the original scale and application
of the final instrument. The second phase consisted of statistical analysis to assess
sensitivity, specificity and accuracy, in accordance with a previous study. The inter-rater
reliability of the translated scale was assessed using Cohen’s kappa coefficient.
The CPSS[14] consists of three items elaborated from the National Institutes of Health Stroke
Scale (NIHSS). It assesses the presence or absence of facial paralysis, weakness in
the arms and abnormalities of speech[14].
Translation and cross-cultural adaptation
This part of the study involved 10 participants who are recognized in their professional
fields, including neurologists and clinicians, nurses, physiotherapists and native
and Brazilian translators. They performed the translation and cross-cultural adaptation
process in accordance with the methodology described by Beaton et al. 2007[18], in five phases, as follows:
-
Initial translation: The initial translations were performed by two bilingual translators
(T1 and T2), whose native language was Brazilian Portuguese (i.e. the target language).
They had different levels of experience: T1 was a professional with knowledge in the
field of healthcare; and T2 was a professional in another field. Neither T1 nor T2
had seen the original instrument.
-
Synthesis of translations: The initial translations were analyzed and synthesized
into a single version (T12), after careful analysis of divergences between the versions
and resolution of problems.
-
Back-translation: Two professionals translated the T12 version back into the original
language. This phase was intended to ensure that the T12 version reflected the same
content as the items in the original version. Through this, two versions were generated:
BT1 and BT2. This phase aimed to ensure that T12 reflected the same meaning as in
the original version.
-
Expert committee analysis: This committee consisted of researchers and healthcare
professionals, in addition to the translators involved in the previous stages, and
it consolidated all versions of the scale (i.e. T1, T2, T12, BT1 and BT2). Equivalence
in semantics, and idiomatic, conceptual and experiential factors, and the content
for analysis of the instrument, were considered in the analysis.
-
Pre-test of the final version: the researcher interviewed the contributing professionals
regarding possible doubts about the meaning of each item.
The methodological scheme used in this process is shown in [Figure 1].
Figure 1 Methodological scheme used in the translation and cross-adaptation of the Cincinnati
Prehospital Stroke Scale. Brazil, 2019.
Application of the translated scale and cross-cultural adaptation
This stage was performed between October 2016 and December 2017. The final scale was
applied by a SAMU 192 team. Nineteen professionals participated in this stage: eight
doctors, six nurses and five nursing technicians. Application was implemented when
the team arrived at the emergency site in cases of patients with suspected stroke
to which the team had been alerted by the call center. Each professional was responsible
for applying the scale to each patient. In cases in which there were two professionals
in the same service, both performed patient evaluations and applied the scale independently,
so that there was an opportunity to assess inter-rater reliability. All patients were
referred to the stroke center.
At this stage, individuals >18 years of age who were suspected of experiencing stroke,
and who were accompanied by an individual who agreed to authorize the use of patient
data for research purposes, were included in the study. In addition to the data from
application of the final scale, data from the prehospital and hospital records were
also collected.
Statistical analysis
To verify the reliability of the instrument, inter-rater reliability tests were performed
using Cohen’s kappa coefficient among the professionals who performed prehospital
care for the patient, considering the following values: <0.20, poor agreement; 0.20-0.39,
fair agreement; 0.40-0.59 moderate agreement; 0.60-0.79, substantial agreement; and
>0.8, almost perfect agreement[19]. For this analysis, scales that were applied concurrently by two professionals on
the same patient were considered, which was possible in 26 cases (40.6%).
To assess the validity of the scale, the sensitivity, specificity, accuracy, positive
predictive value (PPV) and negative predictive value (NPV) were calculated for all
the instruments applied, considering a 95% confidence interval (95%CI). The final
diagnosis, which was made at the hospital by a neurologist trained in stroke, with
the aid of computed tomography, was taken to be the “gold standard” for all statistical
tests. The term “stroke mimics” was used to classify patients who were not diagnosed
with stroke[20]. The statistical analysis was performed using SAS version 9.4 (SAS Institute, Cary,
NC, USA) for Windows (Microsoft Corporation, Redmond, WA, USA).
Ethics approval was granted by the Botucatu Medical School Research Ethics Committee.
RESULTS
In the first step of this study, translation and cross-cultural adaptation of the
original instrument were performed. In the process of translation into Brazilian Portuguese,
difficulty was encountered with the words “droop” and “slur” because these have several
meanings in the target language. However, the translation of these words was resolved
after several discussions and, finally, a consensus was reached among the expert committee
members. In the process of cross-cultural adaptation, the phrase “the sky is blue
in Cincinnati” was changed to “Brazil is the country of football”, to facilitate patient
understanding and, by extension, the feasibility of applying the instrument because
the original expression is not culturally relevant in the Brazilian context. The original
scale was thus translated and adapted for use in the Brazilian Portuguese language
([Figure 2]).
Figure 2 Translated version of the Cincinnati Prehospital Stroke Screen for use in Brazil.
Brazil, 2019.
After this step, the final scale was applied to the target population, consisting
of 64 patients with suspected stroke, of whom 45 (70.3%) had a confirmed diagnosis:
37 (82.2%) of these were classified as presenting ischemic stroke; 6 (13.4%), hemorrhagic
stroke; and 2 (4.4%), an attack of transient ischemic disease. The data collected
enabled statistical analysis on the use of the scale in a representative sample of
the Brazilian population.
The results demonstrated high inter-rater reliability, as seen from the high value
of Cohen’s kappa coefficient, especially for the items “arm drop” and “speech”, which
reached the maximum value. Although there were small variations in agreement between
the observers for the item “facial paralysis”, agreement remained high (0.8385), as
shown in [Table 1].
Table 1
Cohen's kappa coefficient for the final version of the Cincinnati Prehospital Stroke
Scale, translated and adapted for use in the Brazilian Portuguese language. Brazil,
2019.
|
Scale item
|
k
|
95%CI
|
|
Facial droop
|
0.8385
|
0.6263-1.0000
|
|
Arm drift
|
1.0000
|
1.0000-1.0000
|
|
Speech
|
1.0000
|
1.0000-1.0000
|
95%CI: 95% confidence interval; k: Cohen's kappa coefficient.
The statistical tests revealed accuracy of 93.0% (95%CI 87.8-98.2), sensitivity of
92.4% (95%CI 86.0-98.8; PPV, 71.8) and specificity of 4.0% (95%CI 0-11.7; NPV, 16.7),
in relation to the final gold standard diagnosis. The sensitivity of the scale increased
according to the number of changed items, as follows: 1 abnormal variable, sensitivity=61.0%
(p=0.5429); 2 abnormal variables, sensitivity=77.0% (p=0.0864); and 3 abnormal variables,
sensitivity=88.0% (p=0.4660).
DISCUSSION
In the present study, we translated and performed cross-cultural adaptation of the
CPSS for use in the Brazilian Portuguese language, and then applied it to a sample
target population and analyzed the results obtained. The scale demonstrated its utility
in facilitating early diagnosis of stroke, yielding excellent values for sensitivity,
accuracy and inter-rater reliability.
Worldwide, the process of cross-cultural adaptation has been important to ensure that
scales are interpreted the same way in different languages, thus ensuring applicability
in several countries[18],[21]. However, there is currently no consensus in the literature regarding the strategies
that should be used. Nevertheless, it is clear that it is a complex process that requires
methodological rigor to guarantee the semantic, idiomatic and conceptual equivalence
of the scale in question. In the present study, we opted to follow the theoretical
framework described by Beaton et al.[18], which provides recommendations for the process of translation and transcultural
adaptation of scales. This proposes a process that encompasses five phases: initial
translation, synthesis of translations, back-translation, analysis by an expert committee
and pre-test of the final version. All the steps in the translation and cross-cultural
adaptation of the CPSS were performed, and there was a need to change some terms for
cross-cultural adaptation of the scale, to ensure quality and applicability to the
Brazilian population.
After the process of translation and cross-cultural adaptation, the final scale was
applied to patients with suspected stroke, who were treated by a SAMU 192 team and
referred to a stroke center. This made it possible to analyze the applicability of
the scale. The results from the analysis revealed that the majority of the patients
examined were diagnosed with ischemic stroke, which corroborated global statistics
that have classified this as the most prevalent type of stroke among the world’s population[22]. There is a need to improve the quality of early recognition of stroke and the referral
of patients to a qualified hospital, given the extremely time-sensitive nature of
stroke. The percentage of patients receiving treatment in Brazil remains low, mainly
due to delays in arrival at a hospital. This makes it essential for the healthcare
professionals involved in prehospital care to recognize the signs and symptoms of
stroke, and to implement protocols for proper referral[10].
Inter-rater reliability was analyzed using Cohen's kappa coefficient. This analysis
was performed in 40.6% of the cases, for whom there was the possibility of applying
the scale by two professionals concurrently. There was slight variation in concordance
regarding the facial paralysis item, thus demonstrating difficulty in assessing this
item, which had also been reported in another study[23]. Nevertheless, the values found were considered to be excellent, and did not hinder
the use of this scale.
The latest systematic review to assess the use of instruments for early stroke recognition[11] reported that application of the CPSS in several countries had demonstrated sensitivity
values between 44 and 95%. Considering the data reported in the international literature,
it was evident that the scale translated and adapted for use in the Brazilian population
demonstrated high sensitivity (92.4%), although it demonstrated low specificity (4.0%),
which was also consistent with the literature[11],[12],[13]. In addition, the accuracy of the scale was high (93.0%), which reflected its excellent
accuracy in diagnosing the disease.
It was noted that the sensitivity increased according to the number of items that
presented changes, such that the greater the number of changes was, the greater the
risk was that the patient was actually having a stroke. In this regard, the scale
is an important instrument for systematizing patient care, thereby increasing the
chances of early diagnosis.
The results from the present study revealed that the scale demonstrated excellent
accuracy, sensitivity and inter-rater reliability. The CPSS can assist professionals
in the emergency sectors during the initial assessment of patients with suspected
stroke, and can significantly contribute to early recognition in a simple and fast
manner. Because of its simplicity and objectivity, application of this scale becomes
useful for the entire healthcare team working in prehospital care, and not just the
medical professionals. Considering the configuration of Brazilian prehospital care,
which is formed mostly by professionals from nursing teams, this scale can have a
positive impact on making early diagnoses of stroke and increasing the rates of appropriate
and timely treatment.
There were limitations to the present study. The first of these was our inability
to assess intra-observer reliability, because prehospital care does not allow application
of the scale at two times by the same evaluator. However, we believed that this can
be analyzed during hospital care, given that there is a longer period of contact with
the patient. In addition, we were not able to analyze inter-rater reliability in all
cases because only cases that were attended by the advanced support unit allowed application
by two professionals simultaneously. Nevertheless, we believe that other studies may
confirm this result, which was an excellent rate, despite only being assessed in 40.6%
of the sample.
In conclusion, the CPSS was a useful scale for helping healthcare professionals in
the emergency sectors during the initial evaluation on patients with suspected stroke.
It significantly contributed to early recognition of stroke in a simple and quick
manner, and showed excellent accuracy, sensitivity and inter-rater reliability.
