Obstructive Sleep Apnea in Normal Weight Patients: Characteristics and Comparison With Overweight and Obese Patients

ObjectiveTo determine the frequency of obstructive sleep apnoea (OSA) and metabolic syndrome (MS) in normal weight patients and their characteristics, and to compare these with overweight and obese patients.MethodsWe studied all patients with suspected OSA referred to the sleep laboratory from January to December 2009. OSA was diagnosed when the apnoea-hypopnoea index (AHI) was >5 and symptoms were present. MS was diagnosed according to International Diabetes Federation (IDF) criteria. The patients were distributed into 3 groups according to body mass index (BMI): normal weight (<25 kg/m2), overweight (25–29.9 kg/m2) and obese (≥30 kg/m2).ResultsWe studied 475 patients: 7.60% normal weight and 56.4% obese. Most patients in the normal weight group were women, snorers, non-smokers, non-drinkers and were significantly younger and with a smaller neck and waist circumference than obese and overweight patients. OSA was diagnosed in 90.10%: 77.70% normal weight. OSA in these patients was mostly mild, and there were differences between the diagnosis of OSA and the BMI classified. MS was diagnosed in 64.40%: 33.33% normal weight. There was a higher probability of MS as the BMI increased. OSA and MS frequency in normal weight patients was 22% and in obese patients was 70.52%. OSA in normal weight patients was related with gender and age. There was no relationship between OSA and MS, or between otorhinolaryngological malformations and OSA in normal weight patients. Eight normal weight patients with OSA were treated with continuous positive airway pressure (CPAP) therapy.ConclusionsThe frequency of OSA in normal weight patients was lower than in overweight and obese patients. The frequency of concomitant OSA and MS was lower in normal weight patients than in obese subjects. Normal weight patients were mostly women, younger and had no toxic habits. In normal weight patients, age and gender were predictive factors for OSA, but OSA and MS were not related.

ResumenObjetivoConocer la frecuencia del síndrome de apnea-hipopnea del sueño (SAHS)y del síndrome metabólico (SM) en normopeso y sus características. Determinar si existen diferencias epidemiológicas con aquellos con sobrepeso u obesidad.MétodosSe estudiaron todos los pacientes con sospecha de SAHS remitidos al laboratorio del sueño desde enero a diciembre 2009. Se diagnosticó de SAHS cuando el índice de apnea-hipopnea (IAH) era > 5 y existía clínica. Se diagnosticó el SM según los criterios de la International Diabetes Federation (IDF). Los pacientes se distribuyeron en 3 grupos según el índice de masa corporal (IMC): normopeso (< 25 kg/m2), sobrepeso (25-29,9 kg/m2) y obesidad (≥ 30 kg/m2).ResultadosSe estudiaron 475 pacientes: 7,60% normopeso y 56,40% obesos. De los normopeso, la mayoría eran mujeres, roncadores, no fumadores, no consumían alcohol y eran significativamente más jóvenes y con menor perímetro de cuello y abdomen. Se diagnosticó de SAHS al 90,10%: normopeso 77,70%. En pacientes con SAHS y normopeso la mayoría eran SAHS leve, existiendo diferencias entre diagnóstico de SAHS e IMC categorizado. Se diagnosticó de SM al 64,40%: 33,33% normopeso, encontrando mayor probabilidad de SM al aumentar el IMC. La prevalencia de SAHS y SM simultáneamente en normopeso fue del 22% y en obesos del 70,52%. El SAHS en normopeso se relacionó con el sexo y la edad. No se encontró relación entre SM y SAHS, y tampoco entre malformación otorrinolaringológica y SAHS. Se trató con CPAP a 8 pacientes normopeso con SAHS.ConclusionesLa frecuencia de SAHS en normopeso era menor que en los sobrepeso y obesos. La frecuencia de SAHS y SM simultáneamente en normopeso frente a obesos fue menor. Los pacientes normopeso eran con más frecuencia mujeres, más jóvenes y sin hábitos tóxicos. Los factores predictores de SAHS en normopeso eran sexo y edad, sin que existiera relación entre SM y SAHS.