Takaisin

Näkökenttäprogression insidenssi

Näytönastekatsaukset
Anja Tuulonen
22.8.2014

Näytön aste: C

Näkökenttäprogression insidenssi vaihtelee huomattavasti ja riippuu suurimmaksi osaksi käytetyistä menetelmistä. Puutoksen laajuus ja seurannan pituus selittänevät viidenneksen heterogeenisyydestä, 80 % johtunee menetelmistä

Katsaus «Ernest PJ, Viechtbauer W, Schouten JS ym. The infl...»1

A systematic computerized search was performed in PubMed, EMBASE, and all databases and registers of The Cochrane Library, in April 2009 The search was limited to articles in English, Dutch, French, or German. A total of 2450 articles were identified. All titles and abstracts were screened, and articles were excluded based on predefined exclusion criteria. Of the remaining 782 articles that were studied completely, 48 articles fulfilled the selection criteria. The selected studies had to follow patients with glaucoma for minimally 1 year with the use of conventional visual field examinations.

Twelve articles that studied 30 methods in ten studies were included in the meta-analysis. All methods were named and classified in six groups according to their main characteristics.

1. Glaucoma progression analysis (GPA)

  • similar to the visual field endpoint in the EMGT study
  • an event analysis based on pattern deviation values and is included in the HFA software.
  • When significant deterioration (p < 0.05) is seen on the pattern deviation probability maps of the GPA printouts in the same three or more points on three consecutive follow-up tests, the software interprets this as likely progression.

2. Group (AGIS & CIGTS)

  • Two methods that were based on the AGIS method, use a scoring system to grade each visual field in the follow-up period.
  • The AGIS score is based on the actual decibel deviations at the total deviation plot, while the CIGTS algorithm is based on the p-values obtained from the total deviation probability plot.
  • Both scoring systems range from 0 to 20, with 0 representing no field loss and 20 end-stage disease.
  • Visual field series are considered to be progressive if the score has a minimal increase of four (with the AGIS method) or three points (with the CIGTS method) and is confirmed by two additional tests.

3. Point-wise linear regression (PLR)

  • a linear regression analysis is performed in different individual locations at the visual field.

4. Linear regression analysis with visual field indices

  • MD
  • Visual field index (VFI) is calculated by the software of the HFA. Each location on the visual field contributes to the VFI, although it is more heavily weighted to central areas of the visual field. A location that is not significantly (p < 0.05) depressed on the pattern deviation probability map is considered to have a 100 % sensitivity. The VFI is expressed as one percentage, where 100 % represents a normal visual field and 0 % represents a perimetrically blind eye. The HFA software performs a linear regression analysis of the VFI against time.

5. Combined a PLR and a linear regression analysis of the MD value

  • The methods in this group were variants of the threshold noiseless trend (TNT) program
  • The TNT program filters perimetric results and takes into account dependency relations in the visual field.
  • Moreover, it combines linear regression analyses of the MD, the cumulative defect curve, and different locations at the visual field.
  • Suspected progression is seen for the first time that one of these parameters indicates progression. If this result is repeated by two consecutive examinations or if two or more parameters indicate progression, TNT indicates definite progression

6. Clinical group - methods based on clinical judgement

  • Classified in this group were methods based on entirely subjective assessments of visual fields by multiple observers, who had to agree on progression while they were blinded for other clinical data.
  • Other methods in this group used certain algorithms for the assessment of visual fields, for example based on the clinical judgement of scotoma’s.
  • One clinical method was based on nonparametric ranking of MD values. This method objectifies the commonly practised method of monitoring glaucoma patients with the use of MD values. A visual field series is considered progressive as the MD value of a follow- up visual field is worse than the MD of the worse of two baseline fields. This has to be confirmed on at least two visual fields.

Population characteristics

  • In total, 1040 eyes of 948 patients with glaucoma were studied in the ten studies included.
  • All patients were derived from western countries, with mean baseline MD values ranging from -3.3 to -10.4 dB, and mean age ranging from 58 to 73 years.
  • An average of 1.7 visual fields per year were analysed in the studies.
  • Patients received various treatments during the follow-up period.

The mean estimated incidence proportion of progression

  • 0.21 (95 % confidence interval (CI) 0.15, 0.26) in 6 years, indicating that on average 21 % of the study eyes progressed in 6 years (range from 2 % to 62 % in 6 years, depending on the method)
  • The incidence proportions of progression according to 30 methods ranged from 0.02 (CI -0.02, 0.05) to 0.62 (CI 0.47, 0.78).
  • GPA was the most frequently studied method, with six studies in this meta-analysis. With an incidence proportion of 0.16 (CI 0.14, 0.19), the GPA is in the middle of the ranking of all 30 methods.
  • The AGIS based methods and most of the methods based on linear regression analysis with indices showed lower incidence proportions than the GPA method.
  • Methods that are based on clinical judgement or the TNT program showed higher incidences than the GPA.

Factors associated with incidence of progression

  • Follow-up time was significantly associated with the incidence of progression, with an increase in the incidence proportion of approximately 2.1 per cent points per extra follow-up year (p < 0.001).
  • Baseline MD was also significantly associated with the incidence of progression, increasing the incidence proportion by 0.9 per cent points per extra dB of MD loss (p = 0.025). No accelerating (quadratic) relationships between these two predictors and the incidence proportions were found (p = 0.93 and p = 0.77, respectively).
  • Approximately 82 % of the heterogeneity in this analysis can be accounted for by the variety of methods used in studies. The rest of the heterogeneity was explained by the mean baseline MD value and the meanfollow-up time.
  • Tutkimuksen laatu: tasokas
  • Sovellettavuus suomalaiseen väestöön: hyvä

Comment

The results of the model can only be generalized for clinically treated glaucoma patients with a mean baseline MD value around -7 dB and a mean follow-up time of 6 years. The estimates of progression should be corrected by adding 0.9 % to the incidence or by subtracting 0.9 % from the incidence, for each dB decrease and increase in baseline MD value, respectively. In the same way, the incidences should be corrected by adding 2.1 % for each year extra follow-up. The chosen method accounted for nearly all differences in the incidence of progression that we found in the included studies, with the exception of the part that can be explained by the baseline MD value and the follow-up time.

Kirjallisuutta

  1. Ernest PJ, Viechtbauer W, Schouten JS ym. The influence of the assessment method on the incidence of visual field progression in glaucoma: a network meta-analysis. Acta Ophthalmol 2012;90:10-9 «PMID: 20942855»PubMed