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Table 3 Characteristics of studies included in the meta-analysis

From: Lower estimated glomerular filtration rates in patients on long term lithium: a comparative study and a meta-analysis of literature

Study

Methods

Results (values are given as mean ± SD)

Comments

Hullin et al. [10]

Comparative study

Mean duration of lithium treatment; 8.3 ± 2.8 years

GFR assessed by creatinine clearance

Lithium group; 30 patients

GFR of lithium group; 61.1 ± 30.2 ml/min

 

Control group; age and gender matched 30 psychiatric patients not on lithium

GFR of controls; 81.3 ± 52.0 ml/min

 

Bendz et al. [11]

Comparative study

Mean duration of lithium treatment; 5.7 ± 2.7 years

GFR assessed by endogenous creatinine clearance was taken for meta-analysis

lithium group; 32 patients

GFR of lithium group; 90 ml/min

 

Control group; 32 age and gender matched psychiatric patients not on lithium

GFR of controls; 94 ml/min

 

Hetmar et al. [13]

Comparative study

Mean duration of lithium treatment; 10 years

GFR assessed by endogenous creatinine clearance was taken for meta-analysis

lithium group; 32 patients

GFR of lithium group; 88.8 ± 18.0 ml/min

When corrected for the age difference, there was no significant difference between the GFR of two groups

Control group; 53 non matched patients with affective disorders not on lithium

GFR of controls; 101.4 ± 21.6 ml/min

 

Bendz et al. [12]

Comparative study

Mean duration of lithium treatment; 18 years

GFR assessed by endogenous creatinine clearance

lithium group; 13 patients

GFR of lithium group; 69 ± 4 ml/min

 

Control group; 13 age and gender matched psychiatric patients not on lithium

GFR of controls; 78 ± 4 ml/min

 

Coskunol et al. [14]

Comparative study

Mean duration of lithium treatment; 4.5 ± 3.9 years

This is the only study that showed the lithium group to have a higher GFR value. However, the numbers in control group were few and they were not matched for cases.

lithium group; 107 patients

GFR of lithium group; 86.5 ± 21.6 ml/min

GFR assessed by endogenous creatinine clearance

Control group; 29 psychiatric patients not on lithium and without bipolar affective disorder

GFR of controls; 83.9 ± 20.5 ml/min

 

Turan et al. [15]

Comparative study

Mean duration of Lithium treatment (for long term users); 6.6 ± 2.0 years

GFR assessed by endogenous creatinine clearance

Lithium group; 20 patients (10 as short term users and 10 as long term users)

GFR of long term lithium group; 72.8 ± 30.9 ml/min

Considering the average duration of lithium use in other studies of the meta-analysis, long term lithium users were the appropriate group to include in the analysis in our opinion.

Long term users had a duration of use more than 3 years

GFR of controls; 125.3 ± 18.1 ml/min

(please also see the comments in discussion)

Control group; 10 lithium naïve unmatched patients with bipolar affective disorder

  

Tredget et al. [16]

Comparative study

Mean duration of Lithium treatment; 15.6 ± 6.4 years

GFR was estimated with the modification of diet in renal disease (MDRD) study formula using the serum creatinine value and other parameters

Lithium group; 61 patients

eGFR of long term lithium group; 66.1 ± 15.5 ml/min

 

Control group; 53 non lithium using patients with affective disorders

eGFR of controls; 75 ± 16.7 ml/min

 

Bocchetta et al. [6]

Comparative study

Duration of lithium treatment; range – 1 to 33 years (mean duration not given), majority were users for more than 10 years according to a figure quoted in article

GFR was estimated with the modification of diet in renal disease (MDRD) study formula using the serum creatinine value and other parameters

Lithium group; 139 patients with bipolar affective disorder

Mean difference of eGFR between cases and controls were; -12 ml/min (95% CI; -17.5 to 6.5 ml/min)

 

Control group; non matched 70 patients with affective disorders not on lithium, regression analysis used to control for confounding factors

  

Rodrigo et al. (This study)

Comparative study

Mean duration of lithium treatment (for long term users); 10.1 ± 7.6 years

GFR was estimated with the modification of diet in renal disease (MDRD) study formula using the serum creatinine value and other parameters

lithium group; 47 patients with bipolar affective disorder

eGFR of lithium group; 79.7 ± 22.6 ml/min

 

Control group; 47 people without a psychiatric illness matched for age, gender and comorbidities (diabetes and hypertension)

eGFR of controls; 89.3 ± 21.3 ml/min