Dialysis Water Scheme - Gov.uk

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Summary of Results External Quality Assessment of Water Microbiology

Dialysis Water Scheme Distribution Number: DW12

Sample Numbers: DW12A, DW12B

Distribution Date: Results Due: Report Date:

March 2017 07 April 2017 19 April 2017

Samples prepared and quality control tested by:

Angela Appea Richard Borrill Thomas Harper Zak Prior Judith Spellar Aneta Stranc Lili Tsegaye

Data analysed by:

Joanna Donn Manchari Rajkumar

Report compiled by:

Joanna Donn Manchari Rajkumar

Authorised by:

Nita Patel

This report must not be reproduced without permission of the organisers. Public Health England Food and Environmental Proficiency Testing Unit (FEPTU) 61 Colindale Avenue London NW9 5EQ Tel: +44 (0)20 8327 7119 Fax: +44 (0)20 8200 8264 Email: [email protected] The data in FEPTU reports is confidential

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For further information about the scheme please refer to: Scheme Guide: https://www.gov.uk/government/publications/food-and-water-proficiency-testing-schemes-scheme-guide Guide to Scoring and Statistics: https://www.gov.uk/government/publications/food-and-water-proficiency-testing-schemes-scoring-systems-and-statistics

General guidance for z-scores:

Participants’ enumeration results are converted into z -scores using the following formula: Z = (xi-Xpt) σpt

xi Xpt

= participants' result (expressed as a log 10 value) = assigned value (participants' consensus median (expressed as a log 10 value))

σpt

= the fixed standard deviation for the examination (calculated by FEPTU)

The σpt-value expresses the acceptable difference between the individual participant’s result and the participants’ consensus median. The σ pt-value used for calculating z-scores in the Dialysis Water Scheme is 0.35. A guide to interpreting z-scores follows, although laboratories must interpret their scores in the context of their own laboratory situation: z = -1.99 to +1.99 z = -2 to -2.99 or +2 to +2.99 z= < -3.00 or > + 3.00

satisfactory questionable unsatisfactory

It is usually recommended that z-scores exceeding ± 2.0 are investigated to establish the possible cause. As a general rule, PHE recommends that all questionable and unsatisfactory results are investigated. FEPTU Quality Control: To demonstrate homogeneity of the sample, a minimum of 10 LENTICULE® discs, selected randomly from a batch, are tested in duplicate for the enumeration test.

To demonstrate stability of the sample, a minimum of nine LENTICULE discs, selected randomly from a batch, are examined throughout the distribution period for the enumeration test. The FEPTU results are determined using a method based on ISO 13959:2014 - Water for haemodialysis and related therapies. The FEPTU results are used for guidance in the preliminary intended results notification, letters are posted on the website immediately after every distribution; electronic notification of their availability is sent to all participants. Refer to section 17.0 of the Scheme Guide if you have experienced difficulties with any of the examinations . https://www.gov.uk/government/publications/food-and-water-proficiency-testing-schemes-scheme-guide

Participants are reminded that reporting incorrect or false negative results for water samples could have serious public health implications. Participants who report unexpectedly high or low results for the enumerations on single occasions only should not be unduly alarmed, although they should still assess the reason(s) for the outlying result.

Please contact FEPTU staff for advice and information: Repeat samples

Carmen Gomes or Kermin Daruwalla

Data Analysis

Manchari Rajkumar or Nita Patel

Microbiological advice

Nita Patel or Zak Prior

General comments and complaints

Nita Patel or Zak Prior

Scheme consultants

Caroline Willis or Julie E. Russell

Scheme Co-ordinator

Nita Patel

Tel: +44 (0)20 8327 7119 Fax: +44 (0)20 8200 8264 Email: [email protected] FEPTU's website

Accreditation: PHE Water EQA Scheme for Dialysis Water is accredited by the United Kingdom Accreditation Service (UKAS) to ISO/IEC 17043:2010.

0006

The data in FEPTU reports is confidential

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Sample: DW12A Contents:

Micrococcus luteus 2.0x10² (wild strain)

Expected Results: All counts are expressed as colony forming units (cfu) per mL. The fixed standard deviation value (σpt value) used for calculation of the z-score is 0.35 for this parameter

Results FEPTU median (MF)¹

200

No. results returned

49

Assigned value (Participants' median all results)

183

Interpretation based on assigned value**

Unsatisfactory/Unacceptable

Uncertainty of assigned value

7

Participants' mean (all results)

177

Expected Range

110 - 256

Standard deviation**

36

No of outlying counts

6

False positives

False negatives

2

Your result

Your interpretation

Score for performance assessment

Z-score

¹ Membrane filtration * Reference: http://ndt.oxfordjournals.org/content/17/suppl_7.toc section IV: Dialysis fluid purity ** Robust S* based on median absolute deviation about the participants’ median (MADe)

Total sent samples

58

Not examined

3

Non returns

6

The data in FEPTU reports is confidential

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Sample: DW12B Contents:

Cryptococcus albidus 83 (wild strain)

Expected Results: All counts are expressed as colony forming units (cfu) per mL. The fixed standard deviation value (σpt value) used for calculation of the z-score is 0.35 for this parameter

Results FEPTU median (MF)¹

83

No. results returned

48

Assigned value (Participants' median all results)

75

Interpretation based on assigned value**

Satisfactory/Triggers action level

Uncertainty of assigned value

3

Participants' mean (all results)

75

Expected Range

45 - 105

Standard deviation**

15

No of outlying counts

6

False positives

False negatives

3

Your result

Your interpretation

Score for performance assessment

Z-score

¹ Membrane filtration * Reference: http://ndt.oxfordjournals.org/content/17/suppl_7.toc section IV: Dialysis fluid purity ** Robust S* based on median absolute deviation about the participants’ median (MADe)

Total sent samples

58

Not examined

3

Non returns

6

The data in FEPTU reports is confidential

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Method based presentation DW12A : Total Viable Counts 17ºC - 23ºC for 7 days

FEPTU Method: Membrane Filtration

Method

Number of Results

Excluded Results

Percentage of the total

Median

Robust S*

Membrane Filtration

15

5

35

150

0

0

-

259

Not Stated

0

2

0

Other

0

0

0

Pour

16

1

38

195

0

87

-

214

Spread

11

1

26

190

0

51

-

250

Range Reported

DW12A - Total Viable Counts 17ºC - 23ºC for 7 days

293

Participants' Median +3SD 292

280 Participants' Median +2SD 256

cfu per mL

240

200 Participants' Median 183 160

120

80

Participants' Median -2SD 110

Participants' Median -3SD 74

2380

2378

FEPTU QC Median

Laboratory identification number

2311

2210 2229

2200

2185

2142

2129

2058

2037

2024

1990

1968

1965

1958

1957

1893

1853

1773

1754

1724

1486

1409

1405

1358

1241

1159

1010

933

1002

532

226 271

166

139 157

126

97 115

9

89

50

Key: reported result by method Membrane Filtration

Not Stated

Other

Pour

Spread

The data in FEPTU reports is confidential

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Sample: DW12A Total Viable Counts 17ºC

Total Viable Counts 17ºC - 23ºC for 7

Total Viable Counts 17ºC - 23ºC for 7

- 23ºC for 7 days

days

days

Method

Media

Standard Method

Membrane Filtration

Other

Other; please state

Membrane Filtration

R2A

European Renal Best Practice

Count

1 1

Guidelines Membrane Filtration

R2A

ISO 13959:2014

Membrane Filtration

R2A

Other; please state

Membrane Filtration

TGEA

European Renal Best Practice

5 1 1

Guidelines Membrane Filtration

TGEA

ISO 11663:2014

Membrane Filtration

TGEA

ISO 13959:2014

Membrane Filtration

TGEA

ISO 23500:2014

Membrane Filtration

TGEA

Other; please state

Membrane Filtration

TGEA

UK Renal Association Guidelines

Membrane Filtration

TSA

ISO 13959:2014

Membrane Filtration

YEA

Other; please state

Pour

R2A

ISO 11663:2014

Pour

R2A

ISO 13959:2014

Pour

R2A

Other; please state

Pour

R2A

PHE guidelines

Pour

R2A

UK Renal Association Guidelines ISO 13959:2014

Pour

TGEA

Pour

TGEA

PHE guidelines

Pour

TGEA

UK Renal Association Guidelines

Pour

YEA

ISO 13959:2014

Pour

YEA

ISO 6222:1999

Pour

YEA

PHE guidelines

Pour

YEA

UK Renal Association Guidelines

Spread

R2A

ISO 11663:2014

Spread

R2A

ISO 13959:2014

Spread

R2A

ISO 23500:2014

Spread

R2A

Other; please state

Spread

TGEA

European pharmacopoeia 5.0

Spread

TGEA

ISO 11663:2014

Spread

TSA

Other; please state

Spread

TSA

UK Renal Association Guidelines

The data in FEPTU reports is confidential

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Method based presentation DW12B : Total Viable Counts 17ºC - 23ºC for 7 days

FEPTU Method: Membrane Filtration

Method

Number of Results

Excluded Results

Percentage of the total

Median

Robust S*

Membrane Filtration

17

2

36

77

0

0

-

Not Stated

0

2

0

Other

0

0

0

Pour

17

0

36

76

0

0

-

97

Spread

12

0

26

70

0

1

-

100

Range Reported

119

DW12B - Total Viable Counts 17ºC - 23ºC for 7 days

120

Participants' Median +3SD 119

Participants' Median +2SD 105

cfu per mL

100

80

Participants' Median 75

60 Participants' Median -2SD 45 40 Participants' Median -3SD 31 20

7 9 52 89 97 115 126 139 157 166 226 271 329 532 933 1002 1010 1159 1241 1358 1405 1409 1486 1724 1754 1773 1853 1893 1957 1958 1965 1968 1990 2018 2024 2037 2058 2129 2142 2185 2200 2210 2229 2311 2378 2380 FEPTU QC Median

0

Laboratory identification number

Key: reported result by method Membrane Filtration

Not Stated

Other

Pour

Spread

The data in FEPTU reports is confidential

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Sample: DW12B Total Viable Counts 17ºC

Total Viable Counts 17ºC - 23ºC for 7

Total Viable Counts 17ºC - 23ºC for 7

- 23ºC for 7 days

days

days

Method

Media

Standard Method

Membrane Filtration

R2A

European Renal Best Practice

Count

1

Guidelines Membrane Filtration

R2A

ISO 13959:2014

Membrane Filtration

R2A

Other; please state

Membrane Filtration

TGEA

European Renal Best Practice

Membrane Filtration

TGEA

ISO 11663:2014

Membrane Filtration

TGEA

ISO 13959:2014

Membrane Filtration

TGEA

ISO 23500:2014

Membrane Filtration

TGEA

Other; please state

Membrane Filtration

TGEA

UK Renal Association Guidelines

Membrane Filtration

TSA

ISO 13959:2014

Membrane Filtration

YEA

Other; please state

Pour

R2A

ISO 11663:2014

Pour

R2A

ISO 13959:2014

Pour

R2A

Other; please state

Pour

R2A

PHE guidelines

Pour

R2A

UK Renal Association Guidelines

Pour

TGEA

ISO 13959:2014

Pour

TGEA

PHE guidelines

Pour

TGEA

UK Renal Association Guidelines

Pour

YEA

ISO 13959:2014

Pour

YEA

ISO 6222:1999

Pour

YEA

PHE guidelines

3 2 1

Guidelines

Pour

YEA

UK Renal Association Guidelines

Spread

R2A

ISO 11663:2014

Spread

R2A

ISO 13959:2014

Spread

R2A

ISO 23500:2014

Spread

R2A

Other; please state

Spread

TGEA

European pharmacopoeia 5.0

Spread

TGEA

ISO 11663:2014

Spread

TSA

Other; please state

Spread

TSA

UK Renal Association Guidelines

The data in FEPTU reports is confidential

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Performance Assessment Sheet Distribution

DW12

DW11

DW10

Sample

Total Viable Counts 17ºC 23ºC for 7 days score

DW12A DW12B DW11A DW11B DW10A DW10B

Total maximum possible score Total percentage

Performance Assessment Comment:

Overall Performance Assessment for Distributions DW12, DW11, DW10

Participants are reminded that to take advantage of the performance assessment overtime tool provided in the reports they need to take part in more than one distribution a year.

100

90-99

80-89

70-79

60-69

50-59

40-49

30-39

20-29

0

10-19

10

1-9

Your overall performance with the enumerations in the dialysis water proficiency testing samples for the current and previous two distributions is collated in the chart to the right.

20

0

Cumulative scores are calculated for the current and previous distribution for the Dialysis Water Scheme. Participants' cumulative scores for each of the examinations are compared with the maximum possible scores after every distribution.

30

Number of participants

Performance assessments are designed to alert participants to on -going problems with their examinations and are provided after every distribution. Scores are allocated to results reported for every parameter, for every sample to help assess performance.

40

Percentage achieved of max possible score for stipulated distributions

Performance Assessment Comment: Laboratories that achieve less than 70% of the maximum possible score are likely to be experiencing significant problems with their examinations and are advised to: a) refer to the relevant distribution reports for sample-specific comments b) refer to the website guidance documents: https://www.gov.uk/government/collections/external-quality-assessment-eqa-and-proficiency-testing-pt-for-food-water-and-environ mental-microbiology

c) contact the organisers for advice

The data in FEPTU reports is confidential

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The data in FEPTU reports is confidential

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The data in FEPTU reports is confidential

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