The Cochrane TAG Specialised Register

The Cochrane TAG Specialised Register

Inclusion criteria

Controlled trials of interventions to change long-term smoking habits in individuals and reduce the prevalence of smoking in the population form the bulk of the specialised register. Interventions to reduce exposure to environmental tobacco smoke (passive smoking) by nonsmokers are included. Controlled studies of the short term effect of nicotine or other drugs on smoking behaviour in smokers will be included in the register but are not at present the subject of reviews. Interventions to help pregnant smokers will be included in the register but will be covered by reviews in the Pregnancy & Childbirth Group. Studies of the effects of smoking or nicotine in smokers and nonsmokers in laboratory situations will not in general be included in the register. Both randomized and non-randomized studies will be included in the Specialised Register. The decision on whether to include non-random studies will be taken individually for each review.
In addition to controlled studies, Interrupted Time Series studies will be included in the Register for population level interventions such as changes in public policy, legislation, advertising bans or taxation.

Since April 2012 the Specialised Register has been managed using the Cochrane Register of Studies (CRS) software. This allows the conversion to a study based register in which multiple reports relating to the same study are linked to a single study record. In future this will also be linked to the trial registration record. Studies in the register which are identified on the basis of the type of intervention as possibly relevant to a particular review are assigned internal keywords in the register. These keywords are not published in CENTRAL. Future plans include indexing study characteristics in¬greater detail, allowing more efficient searching for review updates.

Search strategies for the identification of studies

Electronic searches

·  The Cochrane Central Register of Controlled Trials (CENTRAL) search strategy:

10. SMOK*:TI
14. #1 or #2 or #3 or #4 or #5 or #6 or #7 or #8 or #9 or #10 or #11 or #12 or #13
16. (#14 not #15)

·    MEDLINE (via OVID) search strategy:

1. Randomized Controlled  
2. Controlled Clinical 
3. Pragmatic Clinical 
4. Equivalence 
5. Adaptive Clinical   
6. Clinical
7. Meta      
8. exp Clinical Trial/      
9. Random-Allocation/  
10. randomized-controlled trials/     
11. double-blind-method/       
12. single-blind-method/         
13. placebos/      
14. Research-Design/   
15. ((clin$ adj5 trial$) or placebo$ or random$).ti,ab.   
16. ((singl$ or doubl$ or trebl$ or tripl$) adj5 (blind$ or mask$)).ti,ab.     
17. (volunteer$ or prospectiv$).ti,ab.         
18. exp Follow-Up-Studies/    
19. exp Retrospective-Studies/        
20. exp Prospective-Studies/ 
21. exp Evaluation-Studies/ or [mp=title, abstract, original title, name of substance word, subject heading word, floating sub-heading word, keyword heading word, protocol supplementary concept word, rare disease supplementary concept word, unique identifier, synonyms]        
22. exp Cross-Sectional-Studies/    
23. Comparative study/
24. exp Behavior-therapy/      
25. exp Health-Promotion/     
26. exp Community-Health-Services/        
27. exp Health-Behavior/ or exp Health-Education/     
28. 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12 or 13 or 14 or 15 or 16 or 17 or 18 or 19 or 20 or 21 or 22 or 23 or 24 or 25 or 26 or 27    
29. smoking or exp Smoking Cessation/        
30. tobacco or "Tobacco-Use-Cessation"/      
31. exp Smoking/th [Therapy]
32. "Tobacco-Use-Disorder"/ 
33. Tobacco-Smokeless/       
34. exp Tobacco-Smoke-Pollution/  
35. Smoking reduction/ or Smoking       
36. Smoking prevention/        
37. Vaping/ or      
38. Electronic Nicotine Delivery Systems/ 
39. electronic cigar*.mp.        
40. exp Pipe smoking/ or exp Tobacco smoking/ or exp Tobacco Products/
41. ((quit$ or stop$ or ceas$ or giv$ or abstain* or abstinen*) adj5 (smoking or smoke* or tobacco)).ti,ab.    
42. exp Tobacco/ or exp Nicotine/   
43. 29 or 30 or 31 or 32 or 33 or 34 or 35 or 36 or 37 or 38 or 39 or 40 or 41 or 42 [A category smoking terms]        
44. exp Smoking/ not 43 [B category smoking terms]  
45. 1 or 2 or 3 or 4 or 5 [Likely Controlled trial design terms; RCTs, CCTs, Pragmatic trials, Equivalence trials, Adaptive clinical trials. ]        
46. 43 and 28 [A category smoking+all design terms] 
47. 43 and 45 [A category smoking terms+likely CT design terms]
48. (animals not humans).sh. [used with 'not' to exclude animal studies for each subset]         
49. ((29 or 30 or 32 or 33) and not 46 [Set 4: Core smoking related reviews only] 
50. 44 and 28 [B category smoking+all design terms] 
51. (50 and 45) not 48 [Set 3: B smoking terms, likely CT design terms, human only]
52. 46 not 47 not 48 [Set 2: A smoking terms, not core CT terms, human only]
53. (43 and 45) not 48 [Set 1: A smoking terms, likely CT design terms, human only]

The publication type 'Pragmatic Clinical Trial‘ was added in 2014 and ‘Equivalence Trial’ and ‘Adaptive Clinical Trial’ were added in 2018.

New MeSH terms smoking reduction/, Vaping/, and Electronic Nicotine Delivery Systems/ and free text equivalents were added in 2018. Smoking/pc was replaced by Smoking Prevention/ in 2018 (the term is also retrieved by line 27. exp Health-Behavior/)

Lines 1-27 are study design limiting term, with lines 1-5 identifying almost all the relevant trial reports. Lines 6-27 increase the sensitivity for trials and also identify other evaluations (typically of commmunity based or public policy interventions) which are included in the Register but not submitted to CENTRAL. Lines 29-42 identify almost all relevant papers involving smoking. Papers retrieved only by line 44 generally do not have smoking as a target behaviour or an outcome.
Line 53, combining the core smoking and core trial design terms, identifies the majority of records for the specialised register. Line 52 identifies a small number of additional trials, some other evaluations, and papers useful for the background and discussion section of reviews. Line 51 identifies a small number of additional trials but these are less likely to be relevant to reviews.
Since June 2010 we no longer screen the results of combining line 44 with the lower relevance design terms as the number of relevant reports identified in this subgroup has been very small.

The MEDLINE database includes Epub Ahead of Print, In-Process & Other Non-Indexed Citations.

·    EMBASE (via Ovid) search strategy:

1. random$.ti,ab. 
2. factorial$.ti,ab.
3. (cross over$ or crossover$ or cross-over$).ti,ab.     
4. placebo$.ti,ab.
5. (double$ adj blind$).ti,ab.   
6. (single$ adj blind$).ti,ab.    
7. assign$.ti,ab.   
8. allocat$.ti,ab.   
9. volunteer$.ti,ab.        
10. CROSSOVER       
14. or/1-13 
15. smoking    
16. exp smoking cessation/ or smoking cessation program/ 
17. exp smoking-/ [Not used as single term after Dec 2010] 
18. 17 and (((quit$ or stop$ or ceas$ or giv$ or prevent$) adj3 smok$) or cigarette$).ti,ab.  
19. exp passive smoking/       
20. exp smoking habit/ 
21. smokeless tobacco/ [smokeless added 2010, exp cigarette smoking/ removed August 2013]       
22. smoking reduction/ [added 2018]        
23. 15 or 16 or 18 or 19 or 20 or 21 or 22
24. 14 and 23      

PsycLIT/PsycINFO (via Ovid) search strategy


3. (QUIT$ or CESSAT$).mp.
4. (ABSTIN$ or ABSTAIN$).mp.
7. #2 or #3 or #4 or #5 or #6
11. #8 or #9
12. #7 and #11
13. #10 and #11
14. #1 or #12 or #13

PsycLIT/PsycINFO is also searched for review updates using topic related terms.

·    ISI databases: Science Citations Index (SCI) and Social Science Citations Index (SSCITrial databases

ISI databases are no longer searched for the Register. They may be used for individual reviews will be searched systematically via the CRS to identify relevant controlled trials of smoking cessation interventions. Records will be linked to published reports or identified as currently unpublished. ( is already searched for specific reviews using topic related terms and ongoing trials are listed in the Ongoing Studies section of reviews.)

Hand searching

Below is a list of previously hand-searched resources. Advances in electronic searches have rendered this method unnecessary.



International Journal of Smoking Cessation Volume 1 1992 to Volume 4 Issue 3 1995 (Publication ceased)
Journal of Smoking Related Disorders Volume 1 1990 to Volume 6 Issue 2 1995 (Publication ceased) 
Tobacco Control Volume 1 1992 to Volume 4 1995 (from Volume 5 1996 Tobacco Control is indexed on Medline)
These journals have been searched only for trials within the scope of the review group
Nicotine and Tobacco Research searched from Volume 1 March 1999.


Proceedings of the fifth world conference on smoking and health; 1983 July 10-15; Winnipeg
The Global War. Proceedings of the seventh world conference on tobacco and health. 1990 April 1-5; Perth
Building a Tobacco-Free World. Abstracts of the 8th World Conference on Tobacco or Health; 1992 Mar 30-Apr 3; Buenos Aires
Tobacco and Health. Ninth world conference on tobacco and health; 1994 Oct 10-14; Paris
10th World conference on Tobacco or Health (abstract book); 1997 Aug 24-28; Beijing China
11th World conference on Tobacco OR Health; 2000 Aug 6-11 (abstract book); Chicago (handsearch in progress)
Society for Research on Nicotine and Tobacco 6th Annual Meeting 2000 February 18-20 Arlington Virginia
Society for Research on Nicotine and Tobacco 7th Annual Meeting 2001 March 23-23 Seattle Washington
Society for Research on Nicotine and Tobacco 3rd European Conference 2001 September 19-22; Paris France
Society for Research on Nicotine and Tobacco 8th Annual Meeting 2002 February 21-23; Savannah Georgia
Society for Research on Nicotine and Tobacco 4th European Conference 2002 October; Santander Spain
Society for Research on Nicotine and Tobacco 9th Annual Meeting 2003 February; New Orleans
Society for Research on Nicotine and Tobacco 5th European Conference 2003 November; Padua, Italy
Society for Research on Nicotine and Tobacco 10th Annual Meeting 2004 February; Phoenix Arizona
Society for Research on Nicotine and Tobacco 11th Annual Meeting 2005 March; Prague, Czech Republic
Society for Research on Nicotine and Tobacco 12th Annual Meeting 2006 February;¬Orlando, FL
Society for Research on Nicotine and Tobacco 8th European Conference 2006 September;¬Kusadasi, Turkey
Society for Research on Nicotine and Tobacco 13th Annual Meeting 2007 February;¬Austin, TX
Society for Research on Nicotine and Tobacco 14th Annual Meeting 2008 February; Portland, OR
Society for Research on Nicotine and Tobacco 15th Annual Meeting 2009 April; Dublin, Ireland
Society for Research on Nicotine and Tobacco 16th Annual Meeting 2010 February; Baltimore, Md

Searched for controlled trials and other evaluations relevant to the scope of the review group.

Abstracts from conferences have been submitted to CCTR since Issue 4, 2001.

Other strategies

In 1993 all principal investigators who published trials in smoking cessation were contacted directly to identify unpublished studies.
All studies identified for the U.S. DHHS Agency for Health Care Policy and Research Clinical Practice Guideline on Smoking Cessation and listed in the Guideline Technical Report were assessed for inclusion in the register. (Fiore 1996)