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Table 1 Characteristics of the studies meeting inclusion criteria

From: Which interactions matter in economic evaluations? A systematic review and simulation study

 

Completed studies

Protocols and terminated studies

Overall

Publication yeara

2009

18% (7/40)

50% (7/14)

26% (14/54)

2008

10% (4/40)

14% (2/14)

11% (6/54)

2007

5% (2/40)

29% (4/14)

11% (6/54)

2006

10% (4/40)

0% (0/14)

7% (4/54)

2005

15% (6/40)

0% (0/14)

11% (6/54)

2000–2004

28% (11/40)

7% (1/14)

6% (3/54)

Pre-2000

15% (6/40)

0% (0/14)

9% (5/54)

Mainly/entirely publicly funded

75% (30/40)

100% (14/14)

81% (44/54)

Country where research done

United Kingdom

28% (11/40)

43% (6/14)

31% (17/54)

United States

38% (15/40)

7% (1/14)

30% (16/54)

Other individual country

23% (9/40)

29% (4/14)

24% (13/54)

Multinational

13% (5/40)

21% (3/14)

15% (8/54)

Disease area

Cardiovascular disease

45% (18/40)

0% (0/14)

33% (18/54)

Musculoskeletal

13% (5/40)

14% (2/14)

13% (7/54)

Cancer

15% (6/40)

0% (0/40)

11% (6/54)

Smoking, drugs or alcohol

13% (5/40)

29% (4/14)

17% (9/54)

Other

25% (10/40)

57% (8/14)

33% (18/54)

Factors target different diseases

3% (1/40)

14% (2/14)

6% (3/54)

Type of interventionb

Pharmaceutical

45% (18/40)

36% (5/14)

43% (23/54)

Physiotherapy, exercise and related

15% (6/40)

29% (4/14)

19% (10/54)

Nutrition

8% (3/40)

14% (2/14)

9% (5/54)

Surgery

13% (5/40)

7% (1/14)

11% (6/54)

Training, counselling, incentives and logistical interventions

50% (20/40)

43% (6/14)

48% (26/54)

Sample sizec

Mean (range)

3420 (126, 20,536)

1371 (132, 4733)

3002 (126, 20,536)

< 200 patients

13% (5/39)

7% (1/14)

11% (6/53)

200–999 patients

38% (15/39)

36% (5/14)

38% (20/53)

> 1000 patients

49% (19/39)

29% (4/14)

43% (23/53)

Type of economic evaluation

Cost-effectiveness analysis

68% (27/40)

0% (0/14)

50% (27/54)

Cost-effectiveness and cost-utility analysis

18% (7/40)

43% (6/14)

24% (13/54)

Cost-utility analysis

8% (3/40)

29% (4/14)

13% (7/54)

Cost-consequence analysis

8% (3/40)

0% (0/14)

6% (3/54)

Cost-utility and cost-benefit analysis

0% (0/40)

7% (1/14)

2% (1/54)

Depends on results

0% (0/40)

7% (1/14)

2% (1/54)

Not stated

0% (0/40)

14% (2/14)

4% (2/54)

Cluster-randomised

13% (5/40)

43% (6/14)

20% (11/54)

Type of design

Full factorial

88% (35/40)

86% (12/14)

87% (47/54)

Partial factorial

10% (4/40)

7% (1/14)

9% (5/54)

Incomplete factorial

3% (1/40)

7% (1/14)

4% (2/54)

Factorial matrix size

2 factors & 2 levels2 (e.g. 2 × 2, 2 × 2 + 1, or double 2 × 2)

78% (31/40)

71% (10/14)

76% (41/54)

> 2 factors each with 2 levels (e.g. 2x2x2)

10% (4/40)

0% (0/14)

7% (4/54)

2 factors with > 2 levels on ≥1 factor (e.g. 3 × 2)

10% (4/40)

21% (3/14)

13% (7/54)

> 2 factors with > 2 levels on ≥1 factor (e.g. 3x2x2)

3% (1/40)

7% (1/14)

4% (2/54)

Primary clinical endpoint

Assumed no interaction

53% (21/40)

29% (4/14)

46% (25/54)

Included interaction term

23% (9/40)

7% (1/14)

19% (10/54)

Unclear

25% (10/40)

64% (9/14)

35% (19/54)

Base case economic evaluation

Assumed no interaction

40% (16/40)

7% (1/14)

31% (17/54)

Included interaction term

53% (21/40)

0% (0/14)

39% (21/54)

Unclear

8% (3/40)

93% (13/14)

30% (16/54)

Presentation of uncertainty

None

48% (19/40)

48% (19/40)

Present using confidence intervals and/or scatter graphs

15% (6/40)

15% (6/40)

Cost-effectiveness acceptability curves

Pair-wise comparison(s)

23% (9/40)

23% (9/40)

Multiple comparison(s)

8% (3/40)

8% (3/40)

Pair-wise and multiple comparison(s)

8% (3/40)

8% (3/40)

  1. a Completed studies are categorised by the year when the first paper describing the results of the economic evaluation was published, while protocols are categorised by the date the protocol was published
  2. b Numbers add up to > 100% since 16 studies/protocols evaluated two or more different types of intervention
  3. c Excludes one cluster-randomised study for which the number of patients was not reported