Derivation and validation of a clinical prediction rule for sleep apnoea syndrome for use in primary care.

BACKGROUND: Several clinical prediction rules (CPRs) are available for sleep apnoea-hypopnoea syndrome (OSAH), but they are difficult to apply in primary care (PC). AIM: Derivation and validation of a CPR using simple measurements available in PC. DESIGN & SETTING: A prospective study conducted in health centres from the area of influence of three Spanish hospitals. METHOD: Patients (aged 18-70 years) who attended for any reason; who presented with at least one of the three key symptoms for OSAH (snoring, breathing pauses while sleeping, and daytime sleepiness); and who were not undergoing non-invasive ventilation or prior treatment with continuous positive airway pressure (CPAP) were included. Anthropometric data, smoking habit, comorbidities, and Epworth test were collected. Patients were subsequently referred to the sleep unit (SU), where the decision was taken whether or not to instigate treatment. A multivariate logistic model was constructed using a sub-sample and scores assigned based on the regression coefficients; the CPR was validated with the remaining sample. Both receiver operating characteristic (ROC) curves were plotted and the sensitivity, specificity, and predictive values calculated. RESULTS: The derivation sample comprised 352 patients, with 260 in the validation sample. The final factors (arterial hypertension [AHT], age, body mass index [BMI], and sex) were used to develop a rule with scores ranging from 0.00-5.50. The cut-off point that optimises the area under the curve (AUC) is ≥2.50 points (AUC = 0.78; sensitivity = 86%; specificity = 54%; positive predictive value [PPV] = 45%; negative predictive value [NPV] = 90%; likelihood ratio [LR] = 0.26). The properties for the validation sample with this cut-off point are as follows: AUC = 0.68; sensitivity = 81%; specificity = 43%; PPV = 61%; NPV = 68%; LR = 0.44. CONCLUSION: As in similar cases, the specificity is low, meaning that healthy people are referred to a specialist. A negative result rules out the disease in most cases.

Effectiveness of home single-channel nasal pressure for sleep apnea diagnosis.

INTRODUCTION: Home single-channel nasal pressure (HNP) may be an alternative to polysomnography (PSG) for obstructive sleep apnea (OSA) diagnosis, but no cost studies have yet been carried out. Automatic scoring is simpler but generally less effective than manual scoring. OBJECTIVES: To determine the diagnostic efficacy and cost of both scorings (automatic and manual) compared with PSG, taking as a polysomnographic OSA diagnosis several apnea-hypopnea index (AHI) cutoff points. METHODS: We included suspected OSA patients in a multicenter study. They were randomized to home and hospital protocols. We constructed receiver operating characteristic (ROC) curves for both scorings. Diagnostic efficacy was explored for several HNP AHI cutoff points, and costs were calculated for equally effective alternatives. RESULTS: Of 787 randomized patients, 752 underwent HNP. Manual scoring produced better ROC curves than automatic for AHI < 15; similar curves were obtained for AHI ≥ 15. A valid HNP with manual scoring would determine the presence of OSA (or otherwise) in 90% of patients with a polysomnographic AHI ≥ 5 cutoff point, in 74% of patients with a polysomnographic AHI ≥ 10 cutoff point, and in 61% of patients with a polysomnographic AHI ≥ 15 cutoff point. In the same way, a valid HNP with automatic scoring would determine the presence of OSA (or otherwise) in 73% of patients with a polysomnographic AHI ≥ 5 cutoff point, in 64% of patients with a polysomnographic AHI ≥ 10 cutoff point, and in 57% of patients with a polysomnographic AHI ≥ 15 cutoff point. The costs of either HNP approaches were 40% to 70% lower than those of PSG at the same level of diagnostic efficacy. Manual HNP had the lowest cost for low polysomnographic AHI levels (≥ 5 and ≥ 10), and manual and automatic scorings had similar costs for higher polysomnographic cutoff points (AHI ≥ 15) of diagnosis. CONCLUSION: Home single-channel nasal pressure (HNP) is a cheaper alternative than polysomnography for obstructive sleep apnea diagnosis. HNP with manual scoring seems to have better diagnostic accuracy and a lower cost than automatic scoring for patients with low apnea-hypopnea index (AHI) levels, although automatic scoring has similar diagnostic accuracy and cost as manual scoring for intermediate and high AHI levels. Therefore, automatic scoring can be appropriately used, although diagnostic efficacy could improve if we carried out manual scoring on patients with AHI < 15. CLINICAL TRIALS INFORMATION: Clinicaltrials.gov identifier: NCT01347398.

Effectiveness of three sleep apnea management alternatives.

RATIONALE: Home respiratory polygraphy (HRP) may be a cost-effective alternative to polysomnography (PSG) for diagnosis and treatment election in patients with high clinical probability of obstructive sleep apnea (OSA), but there is conflicting evidence on its use for a wider spectrum of patients. OBJECTIVES: To determine the efficacy and cost of OSA management (diagnosis and therapeutic decision making) using (1) PSG for all patients (PSG arm); (2) HRP for all patients (HRP arm); and (3) HRP for a subsample of patients with high clinical probability of being treated with continuous positive airway pressure (CPAP) and PSG for the remainder (elective HRP arm). METHODS: Multicentric study of 366 patients with intermediate-high clinical probability of OSA, randomly subjected to HRP and PSG. We explored the diagnostic and therapeutic decision agreements between the PSG and both HRP arms for several HRP cutoff points and calculated costs for equal diagnostic and/or therapeutic decision efficacy. RESULTS: For equal diagnostic and therapeutic decision efficacy, PSG arm costs were 18% higher than HRP arm costs and 20% higher than elective HRP arm costs. HRP arm costs tended to be lower than elective HRP arm costs, and both tended to be lower than PSG arm costs if patient costs were omitted. CONCLUSION: Home respiratory polygraphy is a less costly alternative than polysomnography for the diagnosis and therapeutic decision making for patients with suspected obstructive sleep apnea. We found no advantage in cost terms, however, in using home respiratory polygraphy for all patients or home respiratory polygraphy for the most symptomatic patients and polysomnography for the rest.

Significance of including a surrogate arousal for sleep apnea-hypopnea syndrome diagnosis by respiratory polygraphy.

RATIONALE: Respiratory polygraphy is an accepted alternative to polysomnography (PSG) for sleep apnea/hypopnea syndrome (SAHS) diagnosis, although it underestimates the apnea-hypopnea index (AHI) because respiratory polygraphy cannot identify arousals. OBJECTIVES: We performed a multicentric, randomized, blinded crossover study to determine the agreement between home respiratory polygraphy (HRP) and PSG, and between simultaneous respiratory polygraphy (respiratory polygraphy with PSG) (SimultRP) and PSG by means of 2 AHI scoring protocols with or without hyperventilation following flow reduction considered as a surrogate arousal. METHODS: We included suspected SAHS patients from 8 hospitals. They were assigned to home and hospital protocols at random. We determined the agreement between respiratory polygraphy AHI and PSG AHI scorings using Bland and Altman plots and diagnostic agreement using receiver operating characteristic (ROC) curves. The agreement in therapeutic decisions (continuous positive airway pressure treatment or not) between HRP and PSG scorings was done with likelihood ratios and post-test probability calculations. RESULTS: Of 366 randomized patients, 342 completed the protocol. AHI from HRP scorings (with and without surrogate arousal) had similar agreement with PSG. AHI from SimultRP with surrogate arousal scoring had better agreement with PSG than AHI from SimultRP without surrogate arousal. HRP with surrogate arousal scoring had slightly worse ROC curves than HRP without surrogate arousal, and the opposite was true for SimultRP scorings. HRP with surrogate arousal showed slightly better agreement with PSG in therapeutic decisions than for HRP without surrogate arousal. CONCLUSION: Incorporating a surrogate arousal measure into HRP did not substantially increase its agreement with PSG when compared with the usual procedure (HRP without surrogate arousal).

Obstructive sleep apnea and systemic hypertension: longitudinal study in the general population: the Vitoria Sleep Cohort.

RATIONALE: Obstructive sleep apnea and systemic hypertension (SH) are highly prevalent. Although their association has been suggested in cross-sectional studies, conflicting evidence has emerged from longitudinal studies. OBJECTIVES: To assess the association between obstructive sleep apnea and SH in the middle-aged general population. METHODS: A total of 2,148 subjects were included in a longitudinal study of the Vitoria Sleep Cohort, a general population sample aged 30-70 years. We analyzed data on office blood pressure, anthropometric measures, health history, and home polygraphy. Out of 1,557 subjects who completed the 7.5-year follow-up, 377 were excluded for having SH at baseline. The odds ratios for the incidence of SH, according to the respiratory disturbance index (RDI) at baseline, were estimated in 1,180 subjects (526 men and 654 women) after adjustment for age; sex; body mass index; neck circumference; fitness level; and alcohol, tobacco, and coffee consumption. The RDI was divided into quartiles (0-2.9, 3-6.9, 7-13.9, and ≥ 14), using the first quartile as reference. MEASUREMENTS AND MAIN RESULTS: The crude odds ratio for incident hypertension increased with higher RDI category with a dose-response effect (P < 0.001), but was not statistically significant after adjustment for age (P = 0.051). Adjustments for sex (P = 0.342), body mass index (P = 0.803), neck circumference (P = 0.885), and fitness level and alcohol, tobacco, and coffee consumption (P = 0.708) further reduced the strength of the association between RDI and SH. No differences were observed between men and women. CONCLUSIONS: Our findings do not suggest an association between obstructive sleep apnea and the incidence of SH in the middle-aged general population. Long-term follow-up longitudinal studies are needed to better ascertain this association.

[Community-acquired pneumonia due to Legionella pneumophila serogroup 1. Study of 97 cases]. / Neumonía comunitaria por Legionella pneumophila serogrupo 1. Estudio de 97 casos.

INTRODUCTION: Legionella pneumophila is the causal agent of 5% to 12% of sporadic community-acquired pneumonia cases, though rates are changing with the use of new diagnostic methods. METHODS: This is a retrospective study of all patients admitted to our hospital with community-acquired pneumonia due to Legionella pneumophila between 1997 and 2001. Diagnostic criteria included either a positive Legionella serogroup 1 urinary antigen test or seroconversion and a chest radiograph consistent with pneumonia. RESULTS: A total of 97 patients were studied. Ninety cases (92.8%) were community-acquired and 7 (7.2%) were associated with travelling. In 82 cases (84.5%) the presentation was sporadic. Seventy-five patients were smokers (77.3%). The most common symptoms were fever in 91 patients (93.8%) and cough in 67 (68.1%). In five patients (5.2%) creatine phosphokinase concentrations were over 5 times their baseline values (in two over 100 times); four of these patients presented acute renal failure. Seroconversion was observed in 23/42 patients (54.8%). There were no statistically significant differences between the administration of erythromycin or clarithromycin in monotherapy, or in combination with rifampin. Nineteen patients (19.6%) presented acute renal failure and mechanical ventilation was necessary in 22 (22.7%). Twelve patients died (12.5%). Independent prognostic factors associated with death included respiratory rate > 30 breaths/min, urea > 60 mg/dL and PaO2 < 60 mmHg. A significant linear association was found between severity scale scores and the presence of complications or mortality. CONCLUSION: The Legionella urinary antigen test permits early diagnosis and treatment of this disease. The severity scale is an indicator of complications or death.

Neumonía comunitaria por Legionella pneumophila serogrupo 1. Estudio de 97 casos / Community-acquired pneumonia due to Legionella pneumophila serogroup 1. Study of 97 cases

INTRODUCCIÓN. Legionella pneumophila es la responsable del 5 al 12 por ciento de las neumonías extrahospitalarias esporádicas, aunque estas tasas están cambiando con los nuevos métodos diagnósticos. MÉTODOS. Estudio retrospectivo de los enfermos adultos diagnosticados de neumonía comunitaria por Legionella pneumophila ingresados entre 1997 y 2001.Criterios diagnósticos: presencia de antígeno urinario de Legionella serogrupo 1 o seroconversión con radiología de tórax compatible con neumonía. RESULTADOS. Ingresaron 97 pacientes. Noventa casos (92,8 por ciento) fueron comunitarios y 7 (7,2 por ciento) asociados a viaje. En 82 casos (84,5 por ciento) la presentación fue esporádica. Fumaban 75 pacientes (77,3 por ciento). Los síntomas más relevantes fueron fiebre 91 pacientes (93,8 por ciento) y tos 67 (68,1 por ciento). Cinco pacientes (5,2 por ciento) registraron cifras de creatinfosfocinasa superior a 5 veces su valor basal (en dos > 100 veces), cuatro de los cuales presentaron fracaso renal agudo. El antígeno urinario fue positivo en todos los casos, observándose seroconversión en 23/42 pacientes (54,8 por ciento). No se encontraron diferencias estadísticamente significativas entre la administración de eritromicina o claritromicina en monoterapia o en combinación con rifampicina. Presentaron fracaso renal agudo 19 (19,6 por ciento) y precisaron ventilación mecánica 22 (22,7 por ciento). Fallecieron 12 pacientes (12,5 por ciento).Los factores pronósticos independientes con influencia en la mortalidad han sido la frecuencia respiratoria >30 resp./min, urea < 60 mg/dl y PaO2 < 60 mmHg. Se ha observado una asociación lineal significativa entre la escala del índice de severidad y la presencia de complicaciones o la mortalidad. CONCLUSIONES. La determinación del antígeno de Legionella ha permitido un aumento del número de casos, consiguiendo además un diagnóstico y tratamiento precoces. La mortalidad ha sido elevada, siendo la escala del índice de severidad un marcador de la presencia de complicaciones o de mortalidad (AU)