Risk Factors for Small Airway Obstruction among Chinese Island Residents: A Case-Control Study

Abstract

BackgroundWe investigated the prevalence of and risk factors for small airway obstruction (SAO) among Chinese island residents to establish means to prevent and treat SAO.MethodsFrom October 17, 2011 to November 1, 2011, a total of 2,873 residents aged >20 years who lived on the Huangqi Peninsula of Fujian were recruited by random cluster sampling. They were asked to complete a Burden of Obstructive Lung Disease (BOLD) questionnaire and underwent physical examinations and lung function evaluations. SAO was defined as a forced expiratory flow at 50% of vital capacity, Vmax50%, of less than 70% of predicted. Risk factors for SAO were assessed from among demographic and anthropometric variables, blood chemistry results, and questionnaire response items.ResultsA total of 216 (7.52%) Chinese island residents were identified as having SAO (95 males; 121 females). Their survey and test results were compared with 432 age and sex-matched healthy controls (192 males; 240 females) for SAO risk factors. Among numerous factors investigated, only diabetes mellitus (p = 0.039), smoking index (SI, p<0.001 for SI>600), second hand smoke (p = 0.002), and lack of regular exercise (p<0.001) were significant risk factors for SAO.ConclusionsThe risk factors for SAO among Chinese island residents appeared to be similar to those among people who live in high-density urban environments and impoverished rural areas. Public health policies and medical practices directed toward improving respiratory health for island residents should be comparable to those used for urban and rural dwellers.

Spirometry parameters used to define small airways obstruction in population-based studies: systematic review

“…Three studies used FEF 25–75 /FVC [ 35 – 37 ]. Two studies used FEF 25 , FEF 50 or FEF 75 either alone [ 38 ] or in combination [ 39 ]. One study used FEV 3 /FVC [ 40 ] and another used both FEV 3 /FVC and FEV 3 /FEV 6 .…”

“…Ten studies presented criteria defining an abnormal result (Table 1 ), utilising eight separate methods. Three used percent predicted cut offs including: FEF 25–75 < 75% [ 29 ], FEF 25–75 < 67% [ 23 ], and FEF 50 < 70% predicted [ 38 ]. Two used LLN for FEV 3 /FVC [ 12 , 40 ].…”

“…In most studies, age ranged from 18 to 60 years, the smallest contained 74 participants [ 23 ] and the largest 50,479 participants [ 13 ]. Two studies were European [ 32 , 35 ], 2 were from the Americas [ 12 , 29 ], 4 from the Western Pacific [ 13 , 14 , 38 , 40 ] and 1 from South-East Asia [ 23 ]. Five studies were from high-income countries [ 12 , 14 , 29 , 32 , 35 ] and 4 were from low- and middle-income countries (LMICs) [ 13 , 23 , 38 , 40 ].…”

“…Unsurprisingly, there is debate in the scientific community as to the clinical significance of isolated SAO [ 15 , 16 ]. Despite this, population-based studies have attempted to provide estimates of prevalence and associated risk factors [ 13 , 17 ], as well as demonstrate its usefulness as a prognostic marker for future development of chronic respiratory disease, such as COPD [ 18 ]. There is, therefore, an argument that identification of those with isolated SAO in the general population is important, and may highlight an unrecognised potentially symptomatic, clinical population who are at risk of further lung function decline, and in whom intervention may be warranted.…”

Spirometric prediction equations and the relationship between metabolic syndrome and spirometric parameters from an island in Fujian, China

“…Low maximal midexpiratory flow rate is an indicator of small airway obstruction. We have not studied the relationship between MS and its components and this marker for small airway obstruction, but in a previous study, we have reported that diabetes mellitus, high WC, smoking and exposure to second‐hand smoke increase the risk of small airway obstruction, and regular exercise decreases this risk.…”