American Journal of Respiratory and Critical Care Medicine

We evaluated the outcome of the spirometry quality control program of the SA.R.A. multicenter project, the aim of which is the multidimensional assessment of asthma and COPD in the elderly ( ⩾ 65 yr). The factors determining this quality were also evaluated. The program was based on standardized procedures (ATS recommendations), performed by specifically trained and certified personnel; a fully-computerized spirometer with customized software was used for spirometry. A reference center made monthly controls. Overall, 638 cases and 984 controls were examined. Spirometric measurements were obtained in 607 cases and 912 controls; 508 and 747 tests with at least three acceptable curves were obtained in cases and in controls, respectively (NS). The percentage of reproducible tests ranged between 95.8% for FEV1 in controls and 87.6% for FVC in cases. The average reproducibility for FEV1 was 61.6 ml in cases and 58.3 ml in controls (NS). Cognitive impairment, shorter 6-min walk distance, and lower educational level were found to be independent risk factors for a poorer acceptability rate (logistic regression analysis). Male sex and age were risk factors for a poorer reproducibility of FEV1. Reproducibility tended to improve with time (p < 0.001). Although spirometry becomes increasingly difficult in aging patients, a rigorous quality control program can ensure that reliable data are obtained in the majority of patients.

Consequent to progressive population aging in affluent countries, the geriatric aspects of the most common health problems are attracting increasing attention. In this context, chronic obstructive pulmonary disease (COPD) and asthma deserve special consideration because they are underdiagnosed and undertreated (1, 2). One of the reasons for underdiagnosis or misdiagnosis is the limited application of functional measurements in the elderly. Moreover, there is a high prevalence of comorbid conditions with similar symptoms that tend to confound the diagnosis in this age group. Therefore, quantitative assessment of airway obstruction may be even more important in the elderly than in the general population. A good learning capability and dexterity are prerequisites for high-quality spirometry; both these attributes are usually limited to some extent in the elderly, particularly in those affected by chronic airway obstruction. This topic has not yet been sufficiently investigated.

SA.R.A. (acronym from “SAlute Respiratoria nell'Anziano” = “Respiratory Health in the Elderly”) is an ongoing multicenter Italian project designed to investigate various aspects of obstructive pulmonary diseases in patients 65 yr of age and older. It is based on close collaboration among a network of Italian geriatric and pulmonary institutions and the application of standardized and validated methodology. Spirometry was included in the multidimensional assessment.

In organizing a multicenter study involving pulmonary and geriatric teams, based in academic and district hospitals, it is crucial to try to reduce any diversity of competence and experience of investigators. Therefore, measures were taken to ensure spirometry was conducted correctly over time and across centers.

The aims of the present study were to evaluate the outcome of the spirometry quality control program, and to establish the factors determining the quality of spirometric performance in the elderly.


Twenty-four pulmonary or geriatric institutions, distributed throughout Italy (see ) took part in the investigation. The group was coordinated by a scientific committee. Data from individual centers were collected by a coordinating center at the Clinica Pneumologica of the University of Palermo. The coordinating center was also responsible for the quality control, the retrieval, and the final processing of data. The study protocol conformed to guidelines issued by the relevant ethical committee.

All subjects 65 yr of age and older attending the above-cited institutions between January 1, 1996 and July 15, 1997 were enrolled in the study. Subjects with a previous diagnosis of asthma or COPD and/or signs and symptoms compatible with either diagnosis were defined “cases.” Subjects attending the geriatric institutions who did not have a previous diagnosis of respiratory disease (including asthma and COPD) and did not show signs or symptoms compatible with such a diagnosis served as the control group. In all instances, allocation to groups was checked with a questionnaire derived from the IUATLD bronchial symptoms questionnaire (3) modified to include direct questions about an earlier diagnosis of asthma, chronic bronchitis, or emphysema, as well as a question about chronic phlegm for at least 3 mo each year over at least 2 yr. Physical examination and spirometry with reversibility test were included in the diagnostic assessment of subjects.

Exclusion Criteria

Subjects were not enrolled in either group if they had one of the following: severe hepatic failure (B and C grades of the Child index); severe renal failure (plasma creatinine level ⩾ 2 mg/ml); severe cardiac failure (class IV of NYHA); cognitive and/or sensory impairment severe enough to preclude the multidimensional assessment; occurrence of a major psychosocial event (e.g., moving home, loss of work, or death of a close relative) within the previous 6 mo; hospitalization for any reason within the previous 6 mo.

In the case of any acute clinical event not resulting in hospitalization (e.g., fever of any origin, or changes in treatment regimen), the assessment was postponed until at least 2 wk after the event.

Multidimensional Assessment

Multidimensional assessment included: social and environmental aspects (family and housing, education, occupation); personal history (rate of occurrence, periodicity, and precipitating factors of respiratory symptoms, treatment regimen, quality of sleep, and smoking habit); evaluation of physical and mental functioning, with the scales of Barthel (4), Nagi (5), Rosow-Breslau (6), the 6-min walk test (6MWT) (7), the Mini Mental State Examination (MMSE) (8), and the Geriatric Depression Scale (GDS) (9). The Barthel Index is based upon an ordinal scale that weighs 10 items: feeding, bathing, grooming, dressing, bladder control, toileting, chair/bed transfer, mobility, and stair climbing. Subjects can score between 0 (complete dependence) and 100 (complete independence). The Nagi and Rosow-Breslau scales assess more demanding physical activities; they are hierarchically ordered so that the ability to do all nine activities assessed by the Nagi scale (e.g., lifting a weight of 4.5 kg) is a prerequisite for performing one or more of the three activities explored by the Rosow- Breslau (e.g., walking 800 meters); clinical evaluation consisting of physical examination, arterial blood pressure, and anthropometric measurements (weight, height, occiput-wall distance, length of the thigh, abdominal and waist circumference). Anthropometric measurements were obtained according to de Groot and van Staveren (10): in this report they are expressed as body mass index (BMI), i.e., the ratio of weight over the squared height.


Participating centers were given an identical fully-computerized water-sealed Stead-Wells spirometer (Baires System; Biomedin, Padua, Italy), which fulfills the ATS 1994 recommendations for diagnostic spirometry (11). The customized software assists the operator during the test and allows on-line control of compliance with ATS criteria by displaying all the parameters relevant to the start-of-test and end-of-test, as well as those relevant to reproducibility of FEV1 and FVC. The software is designed to save all the maneuvers performed, including failures and aborted attempts; the flow-volume plots of all the tests of each subject may be superimposed in different colors for visual inspection. The software is programmed for the final check (i.e., each single maneuver is examined) and validation (i.e., verification of compliance with the criteria established) by the coordinating center. Finally it produces statistical reports.


In December 1995 two staff members assigned to the study by each center underwent a centralized 3.5-d training course. Forty-eight members were trained (25 male, 23 female). Of these, only 10 had previous experience in spirometry, but their overall performance throughout the study was comparable to that of the remaining 38. Two trainees left the study after some months because they moved to another institution, and they were not replaced. Consequently, only one trainee was responsible for performing the tests in two centers. The teaching program, consisting of 15 h of lectures and workshops, covered various aspects of the diseases to be investigated, the rationale and practice of spirometry and the ATS 1994 standardized procedures. Trainees also received instruction about problems peculiar to geriatric patients, in particular, possible impairment of cognitive capacity and functioning, and they were encouraged to help the elderly in performing the spirometric maneuvers. The program included individual and group sessions on the calibration, use, and maintenance of the instrument. At the end of the course trainees underwent a written and practical examination to verify their understanding of the technique, and all were certified after passing both examinations. No trainee was decertified during the study.

After 1 yr of activity, in December 1996, all trainees attended a 1-d meeting in which the performance of each center and the overall achievements of the project were reviewed.

Monitoring and Quality Control Procedures

All spirometric maneuvers (including failures) were recorded and sent by diskette each month to the coordinating center where each spirogram was reviewed for acceptability and reproducibility, and statistics of the current performance were produced.

An analytical report of performance was regularly sent to the centers. Telephone consultations were frequent. Site visits for repeat training sessions or for technical troubleshooting were made when a problem arose.

Statistical Evaluation

Standard statistical methods were applied by means of the Epi Info (CDC, Atlanta, GA, and WHO, Geneva, Switzerland) and of the Stata software packages (Stata Corporation, College Station, TX).

Differences between groups were analyzed by χ2 for dichotomous variables. In case of continuous variables Student's t test or the Mann-Whitney test was applied, depending upon the occurrence of normal distribution and the homogeneous variance of variables.

Correlates of acceptability, reproducibility, and combined acceptability plus reproducibility of spirometric performance were analyzed first by univariate analysis. For each of these three outcomes, significant correlates (univariate analysis) were then entered into a logistic regression analysis. The independent variable was considered to predict the outcome if its odds ratio (OR) differed from 1 and if the 95% confidence limits did not include 1.

The χ2 for trends test was used to evaluate the effect of the ongoing performance of centers, as reflected by the levels of reproducibility and acceptability of spirometric tests achieved during the study.

The main characteristics of the groups are presented in Table 1. The sample consisted of 638 cases (413 male, 225 female), 73.3 ± 5.9 yr of age (mean ± SD) and 984 controls 73.5 ± 6.3 yr of age (455 male, 529 female). The main results of the multidimensional assessment are listed in Table 2.


Cases (n = 638)Controls (n = 984 )p Value
Age, yr X 73.373.5
SD 5.9 6.3NS
SexM413455< 0.001
BMI, kg/m2 X 26.526.3
SD 4.3 4.2NS
Smoking habitCS104101
FS343366< 0.001
Educational⩽ 5 yr413597NS
> 5 yr218380

Definition of abbreviations: BMI = body mass index; CS = current smokers; FS = former smokers; NS = nonsmokers.


CasesControlsp Value
Barthel score X  92.7 94.6< 0.001
SD  8.1  6.7
6MWT, m X 308.7335.8< 0.001
MMSE, score X  26.5 27< 0.01
SD  3.8  3.2
GDS, score X   4.4  3.6< 0.001
SD  3.4  3.3
FEV1, %pred X  69.5 99.8< 0.001
SD 26.5 19.6
FEV1/FVC X  60.1 75.5< 0.001
SD 15.5  8.6

Definition of abbreviations: Barthel score = index of physical fitness; GDS = Geriatric Depression Scale; the score is an index of depression; MMSE = Mini Mental State Examination; the score is an index of cognitive function; 6MWT = 6-min walk test.

It was not possible to perform spirometry in 91 subjects (25 cases and 66 controls) because of early interruption of expiration (2.2%), physical impairment (17.4%), inability to understand the instructions (50%), and refusal (30.4%). The test was ended in six cases and six controls because of total lack of collaboration. Therefore, a total of 1,519 spirometries (607 cases and 912 controls) were obtained and examined.

According to the ATS start-of-test and end-of-test criteria (11), tests with at least three acceptable curves were 508 (83.6%) in cases and 747 (81.9%) in controls; the difference was not significant. A slight but significant decrease in acceptability (p < 0.01) was recorded after bronchodilatation, i.e., 74.1% of tests included at least three acceptable curves.

Compliance with individual ATS criteria was variable (Table 3). The best results for acceptability were obtained for fulfillment of the extrapolated volume criterion: tests with at least three curves with an extrapolated volume less than 5% of FVC or 0.15 L (whichever was greater) numbered 526 (86.6%) in cases and 741 (81.2%) in controls (p < 0.05). Among the alternative end-of-test criteria, the least satisfactory results concerned the end-plateau time: acceptable tests (i.e., a minimum of three curves with a plateau of at least 1 s) were 246 (40.5%) among cases and 538 (58.9%) among controls (p < 0.001).


CasesControlsp Value
Acceptability, n (%)508 (83.6)747 (81.9)NS
PEFT, n (%)405 (66.7)550 (60.3)< 0.05
BEV, n (%)526 (86.6)741 (81.2)< 0.05
FET, n (%)526 (86.6)748 (82)< 0.05
EEP, n (%)246 (40.5)538 (58.9)< 0.001
FEV1 reproducibility, n (%)573 (94.3)874 (95.8)NS
FVC reproducibility, n (%)532 (87.6)830 (91)NS
FEV1, repr + accept, n (%)487 (80.2)725 (79.4)NS

Definition of abbreviations: BEV = back-extrapolated volume (acceptable if less than 150 ml or 5% of FVC); EEP = end-expiratory plateau (acceptable if no change in volume for at least 1 s); FET = forced exhalation time (acceptable if longer than 6 s); FEV1 reproducibility = if the difference between the largest FEV1 and the second largest FEV1 was lower than 200 ml; FVC reproducibility = if the difference between the largest FVC and the second largest FVC was lower than 200 ml; PEFT = time-to-PEF (acceptable if less than 120 ms).

*No. (%) of tests that meet acceptability and reproducibility criteria.

Reproducibility was very high: the rate of reproducible tests (ATS recommendations) ranged between 95.8% for FEV1 in controls and 87.6% for FVC in the case sample. These rates increased after bronchodilatation (96.5% for FEV1, NS; 93.2% for FVC, p < 0.05). Average reproducibility (expressed by the difference between the largest FEV1 and second largest FEV1) was 61.6 ml in cases and 58.3 ml in controls (NS); for FVC it was 97.3 ml in cases and 83.7 ml in controls (p < 0.01). The distribution of FEV1 reproducibility is shown in Figure 1. If only tests with at least three acceptable curves are considered, FEV1 reproducibility further improves, and the difference between the largest FEV1 and second largest FEV1 decreases to 54.5 ml in cases and to 53.9 ml in controls, whereas for FVC it decreases to 92.7 ml in cases and to 77.7 ml in controls.

Tests meeting both ATS acceptability (three curves) and FEV1 reproducibility criteria were 487 (80.2%) in cases and 725 (79.4%) in controls (NS). Tests meeting both acceptability and reproducibility criteria were characterized by an average of 4.8 ± 1.7 maneuvers, whereas in tests meeting only one or none of these criteria the average number of maneuvers was 4.8 ± 2.3 (NS). Smoking did not distinguish subjects achieving quality control parameters from the remaining sample.

The determinants of performance quality were evaluated by a stepwise multiple logistic regression analysis, applied to the variables listed in Table 4. As shown in Table 5, lower levels of MMSE score, shorter distance walked in the 6MWT, and lower educational level were independent risk factors for a poorer acceptability. Differently, male sex and age were independent risk factors for poor FEV1 reproducibility, whereas the number of drugs used in treatment, male sex, and age were independent risk factors for poor FVC reproducibility. This spectrum of correlates was confirmed for the outcome of acceptability and reproducibility combined, with age as the most significant correlate. These models were also tested with the number of curves obtained as an additional variable, but the latter was not related to either acceptability or reproducibility.


SexMale versus female
AgeContinous variable
BMI22–30 versus < 22 or > 30
Educational level> 5 yr versus ⩽ 5 yr
GDS score⩾ 7 versus < 7*
MMSE score< 25 versus ⩾ 25*
Barthel score< 92 versus ⩾ 92*
Sleep disturbancesPresent versus absent
Smoking habitFormer versus current or nonsmoker
ClassificationCase versus control
No. of respiratory medicationsContinuous variable
No. of associated diseasesContinuous variable
FEV1 as % predContinuous variable
Distance at the 6MWT⩽ 220 m versus > 220 m*
Wheezing breathlessness during
 previous 12 moPresent versus absent

For definition of abbreviations, see Tables 1 and 2.

*Corresponding to the 75th percentile.


OutcomesPredictorsOdds RatioConfidence Intervalp Value
PoorMMSE1.591.07–2.37< 0.05
 acceptability< 75th percentile
6MWT1.571.09–2.26< 0.05
< 75th percentile
Educational1.541.08–2.20< 0.05
 level ⩽ 5 yr
Poor FEV1 Male sex3.041.44–6.42< 0.001
 reproducibilityAge1.051.01–1.10< 0.05
Poor FVC Respiratory1.401.21–1.62< 0.001
 reproducibility drugs, n
Male sex1.991.26–3.12< 0.005
Age1.041.01–1.07< 0.01
PoorAge1.041.02–1.06< 0.001
 FEV1 repr + acceptRespiratory1.171.05–1.32< 0.01
 drugs, n
Male sex1.631.22–2.16< 0.01
MMSE1.541.08–2.20< 0.05
< 75th percentile
Educational1.391.04–1.87< 0.05
 level ⩽ 5 yr

For definition of abbreviations, see Table 2.

Some inequality of performance was recorded across the centers. To evaluate whether inequality was related to differences in the examined sample, we distinguished between higher performance (HP) centers (i.e., with acceptability rate ⩾ 80%) and lower performance (LP) centers (acceptability < 80%). The characteristics of patients recruited in these two groups were statistically compared. The series examined by LP centers included a higher number of cases (294 of 675 subjects examined, 43.6% versus 344 of 947, 36.3% in HP centers, χ2, p < 0.01). On average, subjects examined by LP centers scored lower on the Barthel scale (93 ± 8.2 versus 94.5 ± 6.6) and on the MMSE (26.1 ± 3.7 versus 27.3 ± 3.1) and performed worse at the 6MWT (305.9 ± 128 versus 338.3 ± 122 m) (p < 0.001 for all these comparisons).

To evaluate the effect of time and experience on the performance of centers, we examined the rates of acceptability and reproducibility month by month, and evaluated the significance of the trends. As shown in Figure 2, the percentage of reproducible FEV1 tests increased from 94.2% at the start of the study to a maximum of 95.8% at the end; the trend to improvement of reproducibility over time was significant (χ2 for trends: 4.97, p < 0.05). Conversely, the change of acceptability did not show any significant trend (χ2 for trends: 0.52, p = 0.47).

The performance was related to the workload of centers, as demonstrated by the significant linear correlation between the percentage of acceptable tests (i.e., tests with at least three acceptable curves) of individual centers and the number of tests performed (r: 0.412, p < 0.05); a similar correlation was found for FEV1 reproducibility (r: 0.465, p < 0.05) (Figure 3).

Spirometry is the single most important test for the evaluation of respiratory function in chronic obstructive airway diseases. Pulmonary function declines with age; however, it has not yet been established to what extent the quality of spirometric performance may deteriorate with aging and disease. To our knowledge, this is the first investigation specifically devoted to the quality control of spirometric performance in elderly subjects with and without airflow obstruction. The data show that a quality control program results in highly reproducible spirometries in multicenter studies on the elderly, despite differences across centers with diverse backgrounds and experiences. This overall result is achieved also as an effect of experience gained on the field and from the continuous interactive relationship with the reference center.

Thanks to the technical improvement of spirometers, accurate and precise measurements can now be obtained (12). Therefore, it has become increasingly clear that an important source of variability in spirometric test results could be the procedure and in particular the interaction between technician and patient rather than the device used (13). In this perspective, spirometry quality control programs have proved successful in various settings (14-16). The sources of variability may be particularly numerous and important in the elderly. Indeed, in this age group motor and sensory deficits, dementia, depression, malnutrition are among the factors capable of negatively influencing the measurement procedure. Moreover, spirometric assessment is not widely used in many geriatric practices and therefore experience is limited.

Forced expiratory maneuvers represent a physically demanding activity for respiratory muscles and for the rib cage-lung system, to which the majority of the elderly are not accustomed. Advancing age is frequently accompanied by a physical and cognitive decline. Moreover, chronic airflow obstruction, which is the main indication for spirometry, may in itself be responsible for a peculiar pattern of cognitive decline (17). Consequently, the elderly may have difficulty in meeting the requirements of learning and recall of instructions, dexterity, and ability to interact with the technician that are necessary for high-quality spirometry. On this basis, aging may be expected to account for a progressive increase in the prevalence of inability to meet quality criteria.

The few studies of spirometry performance in the elderly mainly concern subjects with preserved mental and physical abilities. Therefore, the results do not necessarily apply to the universe of patients. A case in point is the normative investigation conducted within the Cardiovascular Health Study, where only 145 subjects out of 5,000 from the general population were unable to perform three acceptable and reproducible tests (18). In that study 20.5% of eligible subjects refused to participate, which resulted in participants being healthier and more educated and having less limitation in their activities of daily living. In an early study on subjects 62 yr of age and older, Milne and Williamson (19) found that the percentage of elderly women unable to do spirometry increased with age and was correlated with a diagnosis of dementia. Subsequently, Sherman and colleagues (20) reported that eight (12.3%) of 65 outpatients older than 65 yr of age could not perform three acceptable FVCs and scored lower on tests of psychomotor speed and executive function. The same study illustrates the difficulty in meeting the criterion of a 2-s plateau; in fact, only nine (15.8%) showed an obvious plateau. This phenomenon was not related to impaired cognitive function; it may be due to the fact that aging is associated with a reduction in elastic recoil so that a plateau cannot be achieved unless the expiratory time is prolonged, with a pattern similar to airway obstruction. Inability to meet reproducibility criteria for FEV1, FVC, or both was relatively common (31.6%) and seemed to be related to the obstructive condition since FEV1 was the best predictor of reproducibility.

The importance of a cognitive deficit clearly emerges from a study (21) conducted in 208 institutionalized subjects characterized by their greater age (83.7 ± 8.2 yr) and more severe mental deterioration than subjects reported in other investigations: only 85 (40.9%) were able to perform spirometry, with a definitely poorer performance in subjects with lower MMSE scores. Conversely, the yield in the group of elderly with little or no cognitive impairment was similar (78.3%) to that shown in the previous study.

The present study extends these observations by examining a host of age-related factors relevant not only to the cognitive domain but also to the social, psychologic, and physical domains. In addition, the clinical conditions of the large study sample ranged from a healthy state to severe airflow obstruction.

The risk of a poor reproducibility was low: it was related mainly to male sex and to a lesser extent to increasing age and the number of drugs (the latter factor for FVC only). The higher risk connected with male sex is probably due to the disease and to obstructive dysfunction since in the univariate analysis this variable was strongly correlated to various indicators of disease (i.e., the number of cigarettes smoked, respiratory symptoms, and spirometric indices). The higher FVC and FEV1 values might partially account for the poorer reproducibility observed in men. Therefore, a reproducibility threshold based on percentage difference, as in the earlier ATS recommendations (22), may be more appropriate than one based on difference in absolute FEV1, as in the ATS 1994 recommendations (11). However, any potential advantages of this change must be weighed against the risk of inappropriately classifying as nonreproducible the tests relevant to subjects less tall and with lower lung volumes (which is often the case in elderly people) (23).

Acceptability of spirometric tests was greatly affected by intellectual performance as indicated by the degree of cognitive impairment at MMSE. In addition, it was independently affected by educational level, probably because better educated subjects are more likely to understand technical instructions. This may be a major problem since at present the elderly population is characterized by a lower educational level. These findings clearly illustrate the need for specific training of respiratory technicians; more time must be devoted to teaching the patient, and instructions must be given in understandable jargon.

Acceptability of spirometric maneuvers is also independently correlated to the distance walked in the 6MWT. This finding, obtained after correction for anthropometric variables, and other factors affecting exercise capacity (i.e., clinical condition, the degree of airway obstruction and comorbidity), suggests that physical fitness is a major determinant of the overall quality of the coordinated “explosive” effort. Although this correlation was not affected by correction for BMI, a role of malnutrition cannot be excluded because this condition may impair the effectiveness of expiratory muscle contraction and the ability to walk far.

In conclusion neither age nor obstructive disease is incompatible with highly reproducible spirometric tests in large multicenter clinical or epidemiologic trials on elderly patients, provided a rigorous quality control program is established. The program must include training of investigators on specific problems related to aging, in particular the need to provide instructions readily understandable by subjects with sensory and cognitive limitations and to allow repetition of maneuvers after a suitable rest interval in order to avail oneself of the slow learning procedure shown by some patients. Finally, the failure to meet some of the more stringent acceptability criteria suggests the criteria be adapted to the characteristics of the elderly population (e.g., end-plateau time and percentage reproducibility threshold).

The writers thank G. Torresin and the staff of Biomedin (Padua, Italy) for continuous and dedicated technical assistance. They also are grateful to Jean Gilder for editing the text.

Supported by a research grant from Boehringer Ingelheim Italia under the auspices of Foundazione Italiana per la Ricerca nell'Invecchiamento (F.I.R.I.).

1. Banerjee D. K., Lee G. S., Malik S. K., Daly S.Underdiagnosis of asthma in the elderly. Br. J. Dis. Chest8119872329
2. Dow L.The diagnosis of asthma in older people. Clin. Exp. Allergy241994156159
3. Abramson M. J., Hensley M. J., Saunders N. A., Wlodarczyk J. J.Evaluation of a new asthma questionnaire. J. Asthma281991129139
4. Mahoney F., Barthel D.Functional evaluation: the Barthel Index. Md. State Med. J.14196561
5. Nagi S.An epidemiology of disability among adults in the United States. Milbank Mem. Fund Q. Health Soc.541976439467
6. Rosow I., Breslau N.A Guttman Health Scale for the aged. J. Gerontol.211966556559
7. Guyatt G., Sullivan M., Thompson P.The 6-minute walk: a new measure of exercise capacity in patients with chronic heart failure. Can. Med. Assoc. J.1321985919923
8. Folstein M., Folstein S., McHugh P.Mini-mental state: a practical method for grading the cognitive state of patients for the clinician. J. Psychiatr. Res.121975189198
9. Yesavage J., Brink T., Lum O., Huang V., Adey M., Leirer V. O.Development and validation of a geriatric depression screening scale: a preliminary report. J. Psychiatr. Res.1719823749
10. deGroot, C., and W. vanStaveren. 1988. Nutrition and the elderly: a European collaborative study in cooperation with the World Health Organisation, Special Program for Research on Aging (WHO-SPRA) and the International Union of Nutritional Sciences (IUNS), Committee on Geriatric Nutrition. Manual of Operations. Wageningen, The Netherlands: Euronut 11.
11. American Thoracic SocietyStandardization of spirometry: 1994 update. Am. J. Respir. Crit. Care Med.152199511071136
12. Nelson S., Gardner R., Crapo R., Jensen R.Performance evaluation of contemporary spirometers. Chest971990288297
13. Crapo R.Spirometry: quality control and reproducibility criteria. Am. Rev. Respir. Dis.143199112121213
14. Enright P., Johnson L., Connett J., Voelker H., Buist S.Spirometry in the Lung Health Study: 1. Methods and quality control. Am. Rev. Respir. Dis.143199112161223
15. Kunzli N., Ackermann-Liebrich U., Keller R., Perruchoud A., Schiendler C.the Sapaldia teamVariability of FVC and FEV1 due to technician, team, device and subject in an eight centre study: three quality control studies in SAPALDIA. Eur. Respir. J.81995371376
16. Stoller J., Buist A., Burrows B., Crystal R. G., Fallat R. J., McCarthy K., Schluchter M. D., Soskel N. T., Zhang R.the α1-antitrypsin Deficiency Registry Study GroupQuality control of spirometry testing in the registry for patients with severe α1-antitrypsin deficiency. Chest1111997899909
17. Incalzi R. A., Gemma A., Marra C., Muzzolon R., Capparella O., Carbonin P.Chronic obstructive pulmonary disease: an original model of cognitive decline. Am. Rev. Respir. Dis.1481993418424
18. Enright P., Kronmal R., Higgins M., Schenker M., Haponik E.Spirometric reference values for women and men 65 to 85 years of age. Am. Rev. Respir. Dis.1471993125133
19. Milne J. S., Williamson J.Respiratory function tests in older people. Clin. Sci.421972371381
20. Sherman C. B., Kern D., Richardson E. R., Hubert M., Fogel B. S.Cognitive function and spirometry performance in the elderly. Am. Rev. Respir. Dis.1481993123126
21. Carvalhaes-Neto N., Lorino H., Gallinari C., Escolano S., Mallet A., Zerah F., Harf A., Macquin-Mavier I.Cognitive function and assessment of lung function in the elderly. Am. J. Respir. Crit. Care Med.152199516111615
22. American Thoracic SocietyStandardization of spirometry: 1987 update. Am. Rev. Respir. Dis.136198712851298
23. Hankinson J., Bang K.Acceptability and reproducibility criteria of the American Thoracic Society as observed in a sample of the general population. Am. Rev. Respir. Dis.1431991516521
Correspondence and requests for reprints should be addressed to Prof. Vincenzo Bellia, Clinica Pneumologica dell'Università, via Trabucco 180, 90146 Palermo, Italy. E-mail:


No related items
American Journal of Respiratory and Critical Care Medicine

Click to see any corrections or updates and to confirm this is the authentic version of record