1 Smith SM, Fahey T, Smucny J, Becker LA. Antibiotics for acute bronchitis. Cochrane Database Syst Rev 2004; 4:CD000245.
2 Diehr P, Wood RW, Bushyhead J, Krueger L, Wolcott B, Tompkins RK. Prediction of pneumonia in outpatients with acute cough—a statistical approach. J Chronic Dis 1984; 37:215-25.
3 Flanders SA, Stein J, Shochat G, Sellers K, Holland M, Maselli J, et al. Performance of a bedside C-reactive protein test in the diagnosis of community-acquired pneumonia in adults with acute cough. Am J Med 2004; 116:529-35.
4 Gennis P, Gallagher J, Falvo C, Baker S, Than W. Clinical criteria for the detection of pneumonia in adults: guidelines for ordering chest roentgenograms in the emergency department. J Emerg Med 1989;7:263-8.
5 Gonzalez Ortiz MA, Carnicero BM, Varela EM. [Prediction of the presence of pneumonia in adults with fever]. Med Clin (Barc) 1995;105:521-4.
6 Heckerling PS, Tape TG, Wigton RS, Hissong KK, Leikin JB, Ornato JP, et al. Clinical prediction rule for pulmonary infiltrates. Ann Intern Med 1990; 113:664-70.
7 Hopstaken RM, Muris JW, Knottnerus JA, Kester AD, Rinkens PE, Dinant GJ. Contributions of symptoms, signs, erythrocyte sedimentation rate, and C-reactive protein to a diagnosis of pneumonia in acute lower respiratory tract infection. Br J Gen Pract 2003; 53:358-64.
8 Khalil A, Kelen G, Rothman RE. A simple screening tool for identification of community-acquired pneumonia in an inner city emergency department. Emerg Med J 2007; 24:336-8.
9 Melbye H, Straume B, Aasebo U, Dale K. Diagnosis of pneumonia in adults in general practice. Relative importance of typical symptoms and abnormal chest signs evaluated against a radiographic reference standard. Scand J Prim Health Care 1992; 10:226-33.
10 Metlay JP, Fine MJ. Testing strategies in the initial management of patients with community-acquired pneumonia. Ann Intern Med 2003; 138:109-18.
11 Nolt BR, Gonzales R, Maselli J, Aagaard E, Camargo CA, Jr., Metlay JP. Vital-sign abnormalities as predictors of pneumonia in adults with acute cough illness. Am J Emerg Med 2007; 25:631-6.
12 Singal BM, Hedges JR, Radack KL. Decision rules and clinical prediction of pneumonia: evaluation of low-yield criteria. Ann Emerg Med 1989; 18:13-20.
13 Graffelman AW, le Cessie S, Knuistingh NA, Wilemssen FE, Zonderland HM, van den Broek PJ. Can history and exam alone reliably predict pneumonia? J Fam Pract 2007; 56:465-70.
14 Macfarlane J, Holmes W, Gard P, Macfarlane R, Rose D, Weston V, et al. Prospective study of the incidence, aetiology and outcome of adult lower respiratory tract illness in the community. Thorax 2001; 56:109-14.
15 Falk G, Fahey T. C-reactive protein and community-acquired pneumonia in ambulatory care: systematic review of diagnostic accuracy studies. Fam Pract 2009; 26:10-21.
16 Engel MF, Paling FP, Hoepelman AI, van der Meer V, Oosterheert JJ. Evaluating the evidence for the implementation of C-reactive protein measurement in adult patients with suspected lower respiratory tract infection in primary care: a systematic review. Fam Pract 2012; 29:383-93.
17 Holm A, Pedersen SS, Nexoe J, Obel N, Nielsen LP, Koldkjaer O, et al. Procalcitonin versus C-reactive protein for predicting pneumonia in adults with lower respiratory tract infection in primary care. Br J Gen Pract 2007; 57:555-60.
18 Hopstaken RM, Witbraad T, van Engelshoven JM, Dinant GJ. Inter-observer variation in the interpretation of chest radiographs for pneumonia in community-acquired lower respiratory tract infections. Clin Radiol 2004; 59:743-52.
19 Boersma WG, Daniels JM, Löwenberg A, Boeve WJ, van de Jagt EJ. Reliability of radiographic findings and the relation to etiologic agents in community-acquired pneumonia. Respir Med 2006; 100:926-32.
20 Albaum MN, Hill LC, Murphy M, Li YH, Fuhrman CR, Britton CA, et al. Interobserver reliability of the chest radiograph in community-acquired pneumonia. PORT Investigators. Chest 1996; 110:343-50.
21 Donders AR, van der Heijden GJ, Stijnen T, Moons KG. A gentle introduction to imputation of missing values. J Clin Epidemiol 2006;59:1087-91.
22 Little RA. Regression with missing X’s; a review. J Am Stat Assoc 1992; 87:1227-37.
23 Rubin DB. Inferences and missing data. Biometrika 1976; 63:581-90.
24 Butler C, Hood K, Verheij T, Little P, Melbye H, Nuttall J, et al. Variation in antibiotic prescribing and its impact on recovery in patients with acute cough in primary care: prospective study in 13 countries. BMJ 2009; b2242.
25 Woodhead M, Blasi F, Ewig S, Garau J, Huchon G, Ieven M, et al. Guidelines for the management of adult lower respiratory tract infections. Clin Microbiol Infect 2011; 17:E1-59.
26 Harrell FE Jr, Lee KL, Mark DB. Multivariable prognostic models: issues in developing models, evaluating assumptions and adequacy, and measuring and reducing errors. Stat Med 1996; 15:361-87.
27 Sun GW, Shook TL, Kay GL. Inappropriate use of bivariable analysis to screen risk factors for use in multivariable analysis. J Clin Epidemiol 1996; 49:907-16.
28 Austin PC, Goel V, van WC. An introduction to multilevel regression models. Can J Public Health 2001; 92:150-4.
29 Greenland S. When should epidemiologic regressions use random coefficients? Biometrics 2000; 56:915-21.
30 Greenland S. Principles of multilevel modelling. Int J Epidemiol 2000; 29:158-67.
31 Urbach DR, Austin PC. Conventional models overestimate the statistical significance of volume-outcome associations, compared with multilevel models. J Clin Epidemiol 2005; 58:391-400.
32 Steyerberg EW. Clinical prediction models. A practical approach to development, validation, and updating. Springer, 2008.
33 Moons KG, Donders AR, Steyerberg EW, Harrell FE. Penalized maximum likelihood estimation to directly adjust diagnostic and prognostic prediction models for overoptimism: a clinical example. J Clin Epidemiol 2004; 57:1262-70.
34 Miller ME, Hui SL, Tierney WM. Validation techniques for logistic regression models. Stat Med 1991; 10:1213-26.
35 Cals JW, Butler CC, Hopstaken RM, Hood K, Dinant GJ. Effect of point of care testing for C reactive protein and training in communication skills on antibiotic use in lower respiratory tract infections: cluster randomised trial. BMJ 2009; 338:b1374.
36 Christ-Crain M, Jaccard-Stolz D, Bingisser R, Gencay MM, Huber PR, Tamm M, et al. Effect of procalcitonin-guided treatment on antibiotic use and outcome in lower respiratory tract infections: cluster-randomised, single-blinded intervention trial. Lancet 2004; 363:600-7.
37 Pencina MJ, D’Agostino RB Sr, D’Agostino RB Jr, Vasan RS. Evaluating the added predictive ability of a new marker: from area under the ROC curve to reclassification and beyond. Stat Med 2008; 27:157-72.
38 Broekhuizen BD, Sachs A, Janssen K, Geersing GJ, Moons K, Hoes A, Verheij T. Does a decision aid help physicians to detect chronic obstructive pulmonary disease? Br J Gen Pract 2011; 61:e674-9.
39 Kelder JC, Cramer MJ, van Wijngaarden J, van Tooren R, Mosterd A, Moons KG, et al. The diagnostic value of physical examination and additional testing in primary care patients with suspected heart failure. Circulation 2011; 124:2865-73.
40 Kok L, Elias SG, Witteman BJ, Goedhard JG, Muris JW, Moons KG, et al. Diagnostic accuracy of point-of-care fecal calprotectin and immunochemical occult blood tests for diagnosis of organic bowel disease in primary care: the cost-effectiveness of a decision rule for abdominal complaints in primary care (CEDAR) study. Clin Chem 2012; 58:989-98.
41 Schrecengost JE, LeGallo RD, Boyd JC, Moons KG, Gonias SL, Rose CE Jr, et al. Comparison of diagnostic accuracies in outpatients and hospitalized patients of D-dimer testing for the evaluation of suspected pulmonary embolism. Clin Chem 2003; 49:1483-90.
42 Harrell FE Jr. Regression modeling strategies. With applications to linear models, logistic regression, and survival analysis. Springer-Verlag, 2001.
43 R Development Core Team. R: A language and environment for statistical computing. R Foundation for Statistical Computing, 2008.
44 Seamark DA, Backhouse SN, Powell R. Field-testing and validation in a primary care setting of a point-of-care test for C-reactive protein. Ann Clin Biochem 2003; 40:178-80.
45 Hopstaken RM, Stobberingh EE, Knottnerus JA, Muris JW, Nelemans P, Rinkens PE et al. Clinical items not helpful in differentiating viral from bacterial lower respiratory tract infections in general practice. J Clin Epidemiol 2005; 58:175-83.
46 Sin DD, Lacy P, York E, Man SF. Effects of fluticasone on systemic markers of inflammation in chronic obstructive pulmonary disease. Am J Respir Crit Care Med 2004; 170:760-5.
47 Melbye H, Straume B, Brox J. Laboratory tests for pneumonia in general practice: the diagnostic values depend on the duration of illness. Scand J Prim Health Care 1992; 10:234-40.
48 Burkhardt O, Ewig S, Haagen U, Giersdorf S, Hartmann O, Wegscheider K, et al. Procalcitonin guidance and reduction of antibiotic use in acute respiratory tract infection. Eur Respir J 2010; 36:601-7.